Black lentils are great and have an excellent taste. I ate them for the first time at a festivity in a restaurant.
I don't know their recipe, I like to combine different tastes, in this case spicy, sweet and sour.
Black lentils - amount depends on your plans, for a starter calculate about 50 g per person, I added chilies, grated orange peel, wild garlic leaves and salt.
Don't cook them in too much water, they will loose their beautiful black color. Instead make a little "soffrito"and add water slowly until they are cooked as you like them. Then add your other ingedients.