In a small bowl, whisk together the Greek yogurt, lemon juice, half of the garam masala, and turmeric.
Toss the cubed chicken breast in the yogurt mixture and let marinate for at least 15 minutes.
Heat the avocado oil in a large skillet over medium heat. Add the marinated chicken and cook until browned on all sides, then remove from the pan and set aside.
In the same skillet, add the diced onion and sauté until translucent, about 5 minutes.
Stir in the grated ginger, minced garlic, and the remaining garam masala, cooking for 1 minute until fragrant.
Pour in the tomato puree, sea salt, and black pepper. Bring to a gentle simmer.
Return the chicken to the skillet and simmer in the sauce for 10 minutes until the chicken is cooked through and the sauce has thickened.
Prepare the basmati rice according to package instructions (using water or broth).
Serve the chicken tikka masala over the fluffy basmati rice and garnish with freshly chopped cilantro.