Wash and chop the vegetables into small pieces. Wash the lentils and boil them until ready (without letting them get mushy).
Heat the oil and add the vegetables to it. Cook until they soften. Add the lentils to them and while stirring nonstop, saute for another 2-3 min.
Let them cool and season with salt. Mash to a thick consistency.
Using a small cake ring, form burgers and arrange them carefully in an oven dish laid out with baking paper and smeared with oil.
Bake in a preheated oven for 10-12 min. If you'd like them to be crunchier, you can bake a little longer.