Prepare the yogurt sauce by stirring together all the ingredients. Let stand at room temperature if cooking shortly or cover and refrigerate if making ahead. (Allow to come to room temperature before serving).
Cut chicken breasts into 3 pieces length wise, then cube each piece into 3/4"-ish wide pieces.
In a medium bowl, stir together all the marinade ingredients until well combined. Add the chicken and toss to coat well. Cover bowl with plastic wrap and refrigerate for up to 8 hours. (For a quick version, let stand at room temperature to marinade 15-20 minutes.)
Preheat oven broiler to High with oven rack 6-8 inches from the heat source (usually not the top rack position, but one down).
Thread chicken pieces onto the 8 skewers, adding 6-8 pieces per skewer. Place skewers on a baking sheet.
Place into oven under broiler for 10 minutes, then remove from oven, flip over and broil another 5 minutes. Remove from oven and flip over again. Move rack up to top position and return to oven for an additional 2-3 minutes, or until nicely browned.
*If you'd like to warm your tortillas, wrap in foil and pop on a lower rack while you're cooking the chicken.
Place some lettuce on the tortillas. Top with a chicken skewer per taco. Garnish with match-sticked cucumber, fresh cilantro and a dollop of yogurt sauce. Serve with a lime wedge for drizzling. To eat, simply slide the skewer out, leaving the chicken in the prepared taco.
Notes
*Kashmiri chili powder is available at Indian grocers. If you don't have or can't find, substitute with 1/8 tsp cayenne and 3/8 tsp paprika.Be sure to read the notes above this Recipe Card, where I share some valuable tips, options, substitutions and variations for this recipe!