Soak the lentils for at least 1 hour (or even better, overnight), so that they are well hydrated and can be blended better with less liquids.
Coarsely chop the vegetables.
Add all the ingredients in the blender and mix until they all become a homogeneous mass. It may take a few minutes, so if your blender is a bit fragile, do this in intervals (mix, stop, and then, start again).
Put it in the fridge to set for at least 30 minutes, so that all the flavors are better combined.
Take a small amount and form balls or burgers. If they have a lot of liquids, you can squeeze them a bit while you form them.
No need to add flour or anything else. When baked, they tighten and become fantastic.
Sprinkle a bit of oil on them and bake them in a preheated oven at 180° C/356° F for about 30-40 minutes (the exact time depends on your oven).