Combine the smoked ricotta, mashed potato, and egg in a bowl.
Mix in flour and season with salt and pepper to form a dough.
Roll the mixture into balls of 3cm to 4cm.
Boil the dumplings until they rise to the surface.
Remove dumplings with a slotted spoon and drain on kitchen paper.
Fry the onion, garlic, carrot, celery, and peppers in oil until soft.
Add wine, lemon juice, and zest, then reduce the liquid by boiling.
Simmer the lentils and stock for 20-25 minutes until cooked through.
Stir in the parsley and season to taste.
Melt butter in a frying pan over medium heat.
Fry the dumplings until crisp and golden brown.
Serve the dumplings in bowls surrounded by the vegetable casserole.