In a large nonstick skillet, heat oil over medium heat; saute onion and garlic until tender. Add lentils and seasonings; cook and stir 1 minute. Stir in broth; bring to a boil. Reduce heat; simmer, covered, until lentils are tender, 25-30 minutes. , Cook, uncovered, until mixture is thickened, 6-8 minutes, stirring occasionally. Mash lentils slightly; stir in salsa and heat through. Serve in taco shells. Top with remaining ingredients.