Hearty Dutch-style vegetarian meatballs crafted from brown lentils, button mushrooms, oats, and herbs, browned in butter and simmered in a rich savoury onion and mustard gravy.
Sauté the diced onion, minced garlic, and mushrooms in 15g butter for 6 minutes until soft and dry. In a large bowl, mash the cooked brown lentils coarsely with a fork. Add the mushroom mixture, rolled oats, beaten egg, soy sauce, herbs, salt, and pepper.
Mix thoroughly until the mixture binds together. With damp hands, roll into walnut-sized balls (about 12 to 14 meatballs). Chill for 15 minutes to firm up.
Melt the remaining butter in a wide frying pan over medium heat. Add the vegetarian meatballs and fry gently for 8 to 10 minutes, rolling them regularly so they brown evenly on all sides.
Pour the vegetable stock mixed with cornflour around the meatballs in the pan. Bring to a gentle simmer for 4 minutes until the sauce thickens into a glossy savoury gravy coating the meatballs.