Start by putting your boiled lentils, breadcrumbs, grated cheese, olive oil, salt and pepper in a bowl or in a bowl.
Beat well. Form your meatballs. Bake in a preheated oven at 180C for 30 minutes.
In the meantime, if you want, make your sauce. Pour the olive oil into a non-stick pan. Once heated, add the onion, garlic and carrot. Saute for 4-5 minutes and add the tomato. Add salt and pepper and mix well. Add some water and cook for 20 minutes at medium temperature.
Allow your sauce to cool for a while before blitzing it in a food processor to make it more saucey.
Pour the sauce on your meatballs, mix and put back in the oven for 3-4 minutes. Take it out, sprinkle grated cheese on top if you want and enjoy your meatballs with whatever side dish you want or just with some bread.