Cook onion in a swirl of oil, in a skillet over medium heat. Cook until soft, then add garlic, lentils, tomato paste, taco seasoning, and a splash of water. Stir and cook for 8-10 minutes. If you accidentally add to much water, make a cornstarch slurry by mixing 1 tablespoon cornstarch with 2 tablespoons of cold water. Add to the lentils and heat for 1-2 minutes to thicken.
In a small bowl, mix salsa, yogurt, cumin, lime juice, salt, and pepper.
Build salad bowls with lettuce, tomato, cheese, and lentil taco filling.
Drizzle with dressing and serve.
Notes
Keep lentil filling and dressing in separate containers in the fridge. Lentils will keep for 3-4 days. The dressing should be good for up to a week!