Mince the onion, garlic, ginger, and red pepper in a food processor or blender. Add all the spices and yogurt and mince again. Transfer to a bowl and add the chicken. Toss to mix, cover and refrigerate for 4 hours or longer.
When ready to grill, lift the chicken out of the marinade and thread onto skewers. Cook covered on a medium-hot grill, turning occasionally until tender and lightly browned, about 8 minutes per side.
Spoon some of the leftover marinade over the skewers as they cook. When the chicken is done, uncover, turn up the heat and chat the skewers slightly for a few minutes more. Slide chicken off the skewers, heap onto a platter, and sprinkle with lemon juice.