Rinse the lentils and drain them.
In a large skillet, saute the onion and garlic together.
Add the lentils and spices, cook for a minute.
Add the broth and bring to a boil.
Reduce the heat, cover and simmer for about 30 minutes.
Uncover and cook a few more minutes to thicken.
Add the salsa.
Serve in taco shells with lettuce and tomato, if desired.