Season the tenderloin chunks with salt and pepper, and set aside.
Heat a dutch oven or heavy bottomed pan, on stove top over medium heat. Add 1 Tbsp of the olive oil, heat it up, about 30 seconds. Add the sausage and cook until browned.
Remove the browned sausage from the pan, and set aside.
Add half of the diced onions to the pan, and sauté them in the sausage fat, until transparent - about 2 mins.
Add half of the garlic, and saute until fragrant - about 2 mins.
Add the loin chunks, and stir - about a min.
When the loin is cooked and browned, add another Tbsp of olive oil to the pot and add the remaining onions, the carrots and the sausage, stir and sauté about 2 mins.
Add the remaining garlic and sauté until fragrant, about 2 mins.
Add the lentils, the bay leaves and water to cover about an inch over the lentils. Cover the pot and let it cook covered over medium heat until the lentils are soft, approx 40 mins, checking on them every 10-15 mins to make sure the lentils are always under water. If needed, add a bit more water.
When the lentils are cooked, season with salt and pepper to taste. Add lime juice, cayenne and mustard powder and let it simmer for 10 or so more mins.
Serve with lime wedges and a drizzle of olive oil, or over rice.