Cut the chicken into bite-sized pieces and place in a shallow container. Set aside.
To make a marinade for the chicken, whisk together the chili powder, ground coriander, lemon juice, garlic, ginger, salt and pepper. Taste and add more lemon juice as desired. Rub into the chicken pieces and marinate for at least an hour, ideally overnight.
To make the seasoned coating, stir together the cornstarch, flours, 1 teaspoon chili powder, and salt and pepper. Set aside.
Heat the oil in a deep pot to 375º F. Dredge the chicken pieces in the beaten egg, then through the seasoned flours. Carefully deep-fry the pieces, four to five pieces at a time, for 3 to 5 minutes.
Remove from the hot oil, using a slotted spoon, and drain on a paper towel-lined plate.
To make the yogurt sauce, whisk together the yogurt, cumin, the remaining 1/2 teaspoon chili powder, garlic, and salt and pepper.
Serve the chicken pieces warm with the yogurt sauce on the side for dipping. Usually this recipe is served as an appetizer, but it also make for a great entrée.