In a large bowl, combine the yogurt, lemon juice, vegetable oil, ground cumin, ground coriander, paprika, turmeric powder, garam masala, chili powder, grated fresh ginger, minced garlic, salt, and black pepper. Mix well to create the marinade.
Add the chicken thighs to the marinade, ensuring each piece is fully coated. Cover the bowl with plastic wrap and refrigerate for at least 4 hours, preferably overnight for best flavor.
Preheat the grill to medium-high heat (about 400°F / 200°C).
Remove the chicken from the marinade, shaking off excess but do not wipe it off.
Place the chicken thighs on the grill and cook for 10-12 minutes per side, or until the internal temperature reaches 165°F (74°C) and the chicken is cooked through with a slight char.
Remove the chicken from the grill and let it rest for 5 minutes before serving.