Heat butter in large pan to 350 F, place steak, onion, garlic and pepper, let sizzle for 30 seconds.
Flip steak, let cook 20 seconds, separate slices and stir in chili powder, lentils and chili, bring to simmer.
Finish cooking to 165 degrees F and stir in cilantro, salt and pepper.
Divide rice and steak mixture evenly into bowls and drizzle with tzatziki sauce.