The lentils must be fully cooked before you begin. Add enough water to cover them by 2 inches, and gently boil them with NO salt. You can add a bit of kombu (seaweed) to the cooking water while they boil for improved digestibility. Lentils will take about 30 minutes to cook.
While they’re cooking, grate the carrots and dice the onion. Add them to the pot, along with the rolled oats, to cook with the lentils for the last 10 minutes.
When the lentils finish cooking, drain any excess water, mash them a bit, and stir in the nut/seed butter.
Make sure the batter is thick enough that they’ll stick together as burgers, adding more nut/seed butter and/or rolled oats if you need to. Then season with the spices, salt and pepper.
Form the lentil mix into burger shapes. Lay them on a baking sheet (ideally lined with parchment paper so they don’t stick), and bake for 30-40 minutes at 300-350 degrees F.
You can also fry the burgers to cook them more quickly. Add a bit of oil to the pan and cook about 10 minutes on the first side. Flip, and cook another 5-7 minutes.