Whisk all sauce ingredients together in a small bowl. Season to taste with about 1/4 teaspoon salt & 1/8 teaspoon pepper. Cover and refrigerate until ready to use.
Grate the onion into a large bowl using a box grater. Add the remaining kofta ingredients. Season to taste (I add 1 teaspoon salt & 1/2 teaspoon pepper) and mix well with your hands until combined.
With damp hands (I lightly spritz mine with cooking spray), divide the mixture into 8 equal portions. Shape each portion around a skewer (see note 1), forming koftas about 5 inches long and 1 inch thick. Smooth the surface, then repeat with the remaining mixture. Place the formed skewers on a parchment paper lined pan and chill for 20 minutes, or cover and refrigerate longer until ready to cook.
Cook Koftas (Stovetop or Grill):Stovetop: Heat 2 tablespoons oil in a large skillet over medium-high heat. Cook koftas in batches of 4 for 5–6 minutes total, turning to brown evenly on all sides. Add more oil for the next batch if needed.Grill: Preheat grill to medium-high (about 400°F). Grill for 6–8 minutes total, flipping halfway through. Cook 3–4 minutes on the first side, then gently flip with a metal spatula or tongs and cook another 3–4 minutes, or until a thermometer inserted in the center reaches 160°F.The koftas should have dark grill marks, shrink slightly, and no longer be pink. If the sides still look undercooked, roll onto the thinner sides and grill for 1–2 more minutes until cooked through.
Lightly toast pitas (see note 2). Spread yogurt sauce on one side of each pita. Add lettuce, 1–2 koftas, and veggies. Drizzle with more sauce and serve immediately with your choice of sides.
Notes
Note 1: If the skewers don’t fit in your skillet, remove them and cook the kofta like patties instead.Note 2: To toast pita, lightly spray both sides with olive oil cooking spray (or brush with oil). Place directly over gas flames on medium to medium-low heat for a few seconds, using tongs to flip until lightly charred.Storage: Best enjoyed right after cooking. Store leftovers in an airtight container in the fridge for up to 3 days. Reheat in a skillet over low to medium heat until warmed through. The uncooked mixture can also be shaped into patties and frozen. Cook from frozen in a skillet over medium heat for about 5–6 minutes per side.