To make marinade: in a medium bowl, whisk together cumin, paprika, coriander, black pepper, salt, cayenne, cardamom, and turmeric.
Add garlic, yogurt, olive oil, and lemon juice. Mix well.
Place chicken in a ziploc bag and add marinade. Toss to combine and refrigerate for at least two hours, but it's more life changing if you do it overnight.
When ready to bake, allow chicken to come to room temp, at least an hour.
Preheat oven to 425°F.
Add red onion and bell pepper slices to chicken marinade bag and toss to coat.
Line a sheet pan with greased tinfoil and remove chicken and veggies from bag, allowing excess marinade to drip off back into ziploc before setting on pan. Spread out, but get some veg on top of chicken so they cook together all yummy and whatnot. Discard excess marinade.
Bake for 30 minutes, rotating pan and flipping everything over halfway through.
When finished baking, rest chicken on a plate for 5-10 minutes (this is a perfect time to throw in your frozen fries for the naanwiches!!!).
In a medium pan over medium heat, drizzle in some olive oil and allow to heat up. Throw in sliced chicken and pan fry until edges crisp and take you to Flavortown. Toss in your veggies at the end to heat them up again! Taste for salt, adding more if needed.