This easy zucchini relish is what to do with all your Summer zucchini! With added mustard, this relish is perfect on hamburgers or hot dogs or enjoy it with sausage.

zucchini mustard relish in jars with spoon

If you have lots of zucchini to use up, this zucchini mustard relish is a perfect use for it. Zucchini is combined with onions, red peppers, chilli pepper flakes (for just a touch of heat), vinegar and mustard.

Make a half recipe for a small batch of zucchini relish, that makes just a few jars or scale it up to make more jars to can and enjoy over the winter. I love to make small jars to take to BBQs or cookouts as hostess gifts!

Ingredients and Substitutions

Zucchini – for the base recipe, you will need about 6 supermarket-sized zucchini. If you are dealing with large, garden zucchini, be sure to weigh the proper amount to start.

Pickling Salt – pickling salt is a special salt, that is simply pure granulated salt (sodium chloride), without any anti-caking agents or additives. It is ideal for preserves and I highly recommend using this easy-to-find salt when making this relish. Regular table salt isn’t recommended, as it has agents in it that can cause cloudy preserves. Kosher salt (without anti-caking agents) is a decent substitute, but the amount used should be increased by 1/2 (so instead of 1/4 cup of pickling salt, you would use 1/4 cup + 2 Tbsp of Kosher salt).

Red Bell Pepper – red bell pepper adds great flavour and visual colour to this relish. Orange bell pepper would work here, though I don’t recommend green bell pepper, as it has a different flavour profile.

Onion – regular yellow, cooling onions are all you need here.

Mustard Seed – mustard seeds are easily found in spice-like containers in with spice section of the grocery store.

Celery Seed – celery seed is also easily found in most grocery stores in the spice section. Be sure not to confuse it with celery salt, which is different.

Turmeric – turmeric provides a lovely yellow colour to the relish, but doesn’t contribute a lot of flavour. In a pinch, it can be omitted, though the relish will be less yellow in colour.

Cider Vinegar – cider vinegar will produce the nicest relish flavour. In a pinch, white vinegar will work.

Sugar – People are always surprised to see the amount of sugar that is in relish, but it is required to help with both the flavour and the preservation of the relish. I don’t recommend reducing the amount of sugar as it may compromise the food safety of your finished relish.

Cornstarch – cornstarch is used at the end of cooking the relish to thicken the relish. Arrowroot powder would also work. Don’t use flour.

How to Chop the Vegetables for Zucchini Relish

You can chop the vegetables by hand, for a chunkier relish or you can use a food processor, for a finer relish. The choice really depends on your preference and/or how you plan to use your relish. A finer relish is perfect for hamburgers and hot dogs, while a chunkier relish is great for sausages or pork chops.

Step-by-Step Photos

  1. I am making a small batch of zucchini relish here and I used my small food processor here to chop the zucchini.
  2. This is the zucchini after being run through the food processor.
  3. Chop the onions in the food processor as well.
  4. The red pepper can also be chopped up in the food processor.
  5. Combine all the chopped vegetables in a bowl.
  6. After stirring the vegetables together, add the pickling salt and stir in. Allow to stand 1 hour, stirring a couple of times. This process draws the extra moisture out of the vegetables.
  1. After the vegetables have sat with the salt, you should see more liquid in the bowl.
  2. Drain the vegetables and rinse well to remove the salt. Allow to drain well, then use a spoon to press down in the strainer to remove as much liquid as possible.
  3. Meanwhile, combine the brine ingredients in a large, heavy-bottomed pan.
  4. Cook the chopped vegetables in the brine until the vegetables are tender, about 15-20 minutes (depending on how coarse or fine the vegetables are chopped).
  5. When the vegetables are tender, add the cornstarch and water mixture to the pan. This is a thickener, to thicken up the relish.
  6. Cook the relish about 3-5 minutes more, or until a spoon run through the relish leaves a very visible streak, that is slow to fill in. The relish is now ready to spoon into jars.

Recipe Tips

  • This is a super easy relish, with just a bit of chopping to do. You can chop by hand or use a food processor to do the work for you. If you prefer a chunkier relish, chopping by hand is a better option, as the food processor will tend to chop it finer.
  • If you’re starting out with a particularly large zucchini (the one I used was about 5 lbs.!), you’ll probably want to remove some of the seeds. Otherwise, with a normal supermarket-sized zucchini, you’re good to leave the seeds in.
  • This relish is perfect with sausage, pork or on hot dogs or hamburgers. We love it with sausage, especially!

Recipe Yield

  • 1/2 X Recipe – makes about 4 cups of relish (good for 3 small jars, as shown here)
  • 1 X Recipe – makes about 8 cups or relish
  • 2 X Recipe – makes about 16 cups of relish
zucchini relish in jars with spoon

Storing or Canning Zucchini Relish

If you are not preserving/canning the relish (by using a boiling water canner), you must store the relish in the refrigerator, where it will keep well for 2-3 months.

To can/preserve the zucchini relish, spoon into sterilized jars, leaving 1/2-inch headspace. Remove any air bubbles by stirring in the jar, wipe the rims and seal with sterilized lids and rings. Boil in a boiling water canner for 15 minutes to process for longer, shelf-stable storage.

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zucchini mustard relish in jars with spoon

Get the Recipe: Zucchini Relish

A delicious and versatile zucchini relish, with added mustard, that makes it perfect for hot dogs, hamburgers and sausage.
5 stars from 3 ratings
Prep Time: 20 minutes
Cook Time: 20 minutes
Resting Time:: 1 hour
Total Time: 1 hour 40 minutes
Yield: 8 cups


  • 3 lbs. zucchini, unpeeled and cut into 1-inch chunks (about 6 supermarket-sized zucchini)
  • 3 medium onions, chopped
  • 2 medium sweet red peppers, diced
  • 1/4 cup pickling salt, *see Note 1 below for details


  • 2 1/2 cups white granulated sugar, *see Note 2 below for details
  • 1 1/2 cups cider vinegar
  • 2 1/2 teaspoons dry mustard powder
  • 1 teaspoon celery seeds
  • 1/2 teaspoon mustard seeds
  • 1/2 teaspoon turmeric
  • 1/2 teaspoon hot chili pepper flakes, *see Note 3 below for details

To finish relish:

  • 1 Tablespoons cornstarch
  • 1 Tablespoon water


  • You can chop the vegetables by hand or with a food processor. Chopping by hand allows for making a chunkier relish, while the food processor makes a finer relish.
  • In food processor (or by hand with a knife), process zucchini, a few pieces at a time, until mostly small pieces with a few larger pieces. Transfer to a large bowl. Add onions, red peppers and stir to combine. Sprinkle with pickling salt and stir in well. Let stand, uncovered, for 1 hour, stirring occasionally. Drain well, rinse and drain again, pressing out as much moisture as you can with a spoon or the palm of your hand. Set aside.
  • In large heavy-bottomed pan, combine the sugar, vinegar, mustard, celery seeds, turmeric and hot pepper flakes. Bring to boil. Add the drained vegetables. Reduce heat and simmer, stirring often, until vegetables are tender, about 15 minutes.
  • Mix cornstarch with water and stir into relish. Simmer, stirring, until spoon pulled across bottom leaves trail that fills in slowly, about 5 minutes.
  • Pack into four 2-cup sterilized canning jars, leaving 1/2-inch (1 cm) headspace. Remove any air bubbles by running a knife through the mixture. Wipe the rims and seal with sterilized lids and rings. Boil in boiling water canner for 15 minutes to process for longer storage. If not canning in a boiling water canner, you must refrigerate the relish, where it will keep well for 2-3 months.


Note 1: Pickling salt is easily found at most grocery stores. It is highly recommended for this relish recipe, for best results. Kosher salt is an option, as long as it doesn’t have anti-caking agents added. You would need to use 50% more Kosher salt, then the amount specified for pickling salt. Table salt is not recommended.
Note 2: It is not recommended that you alter/reduce the amount of sugar added to the relish, as it contributes to both flavour and aids in preservation and shelf-life. Reducing the sugar could compromise the food safety of the finished relish.
Note 3: The chili flakes add just a touch of heat to the relish and as written, don’t make a spicy relish. If you are looking for more heat, simply increase the amount of red pepper flakes, to taste.
Cuisine: American, Canadian
Course: Preserves
Serving: 1cup, Calories: 313kcal, Carbohydrates: 75g, Protein: 3g, Fat: 1g, Saturated Fat: 0.2g, Polyunsaturated Fat: 0.3g, Monounsaturated Fat: 0.3g, Sodium: 3557mg, Potassium: 614mg, Fiber: 3g, Sugar: 70g, Vitamin A: 1273IU, Vitamin C: 72mg, Calcium: 52mg, Iron: 1mg
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