Boil 2-3 cups of water then lower the heat and simmer the lentils in it for about 30 minutes or until they are softened. Drain any excess water from them.
Run the cooked lentils through a food processor with the salt, pepper, nutmeg, ginger, and cornstarch/potato flour, doing a rough chop a few times.
The result you want is a sticky, kinda pasty consistency but it's okay if there are whole lentils still in there, it's quite good that way. Scrape the mixture into a medium bowl.
Gradually add soymilk to your seasoned lentil "ground beef". You may not need the entire 3/4 cup.
The cornstarch or potato flour should've helped bind the mixture, form patties by hand. You'll get about 10-12 small ones.
Scandanavian cooking often involves frying things in butter. To replicate this, I used Earth Balance. Cut off 1-2 tablespoons Earth Balance and cook the patties in it in a skillet, or use 1-2 tablespoons olive or canola oil to cook the patties for about 6-7 minutes on each side until browned.
This step, the "milk wash" is the next bit of Norwegian authenticity. Bring the soymilk to a boil in a saucepan then a low simmer. Place the browned patties in the soymilk and let simmer on low for 10-15 minutes, then remove with a slotted spoon-- don't get rid of the soymilk if you want to make the gravy though.
If you want to make the gravy, blend a tablespoon or two of cornstarch with a little cold water. I recommend cornstarch because flour doesn't have good thickening properties, and milk will thicken on heat but soymilk won't without a lot of cornstarch.
Add the cornstarch-water mix to the soymilk you used to cook the patties. Add the chopped onion, season with salt and pepper, and stir until thickened.
Regardless of if you make the gravy or not-- serve the lentil kjottkaker with boiled potatoes and peas, and lingonberry sauce (heh I get the jars of it from Ikea.).