Pulse ginger and garlic in a food processor until finely chopped. Add onion and pulse until finely chopped.
Toss chicken with 1 1/2 tsp garam masala and 1 tsp salt. Heat 1 Tbsp olive oil in a large skillet over medium-high heat.
Add chicken and cook, rotating halfway through cooking, until cooked through, about 6 to 7 minutes total. Transfer chicken to a plate.
Heat remaining 1 Tbsp olive oil in same skillet over medium-high heat. Add chopped onion mixture and saute until onions have softened, about 3 minutes.
Add tomato paste, remaining 1 Tbsp garam masala, paprika, and cayenne and cook, stirring constantly, 30 seconds.
Add crushed tomatoes, season with salt to taste, and cook stirring occasionally until mixture is hot, about 2 minutes.
Return chicken to pan and cook 1 minute longer. Remove from heat, stir in Greek yogurt and lemon juice.
Serve warm over basmati rice topped with cilantro leaves.
