Preheat your oven to 350°F (175°C). Grease a loaf pan or line it with parchment paper.
Rinse lentils under cold water. In a pot, combine lentils with three cups of water; bring to a boil, then simmer for about 20-25 minutes until tender.
While lentils cook, heat olive oil in a skillet over medium heat. Sauté onions and garlic until fragrant (about five minutes), then add grated carrots and chopped bell peppers; cook for an additional five minutes until tender.
In a large bowl, mix cooked lentils, sautéed vegetables, breadcrumbs, eggs (or flax eggs), spices, salt, and pepper until combined.
Transfer the mixture into the prepared loaf pan; press down firmly to shape into an even loaf.
Bake for 45-50 minutes until golden brown on top. Allow cooling slightly before slicing.