Whisk together yogurt, garlic, salt, turmeric, garam masala, coriander, and cumin in a large bowl. Stir in chicken to coat; cover with plastic wrap and chill at least 30 minutes or overnight (the longer the more flavorful and tender the chicken gets).

Toast sorghum in a saucepan over medium heat for 5 minutes. Add water and bring to a boil, then reduce to a simmer, cover, and cook until tender, 50–55 minutes. Remove pan from heat, and let steam 5 minutes, covered, then drain. Stir in cilantro, zest, juice, honey, and salt; season with pepper.

In a large pot or Dutch oven, heat oil over medium. Add onion and cook until softened, 8–10 minutes. Add tomato paste, ginger, garam masala, garlic, cumin, pepper flakes, cardamom, and salt; cook 1 minute. Add tomatoes and coconut milk and simmer 20 minutes. Transfer half of the sauce to a blender and purée, then add back to pot with remaining sauce and simmer while cooking chicken.

Coat a cast iron skillet or cast iron grill pan with oil or nonstick spray. Cook chicken (avoid scraping off much of the marinade), in 3–4 batches in skillet until cooked through, about 8 minutes. Transfer cooked chicken to sauce.

Serve Chicken Tikka Masala over Cilantro-Lime Sorghum. Top with cilantro and serve with lime wedges.