For the pesto, roast pine nuts in a pan without fat, remove. Grate the parmesan. Peel garlic and chop coarsely. Wash basil and shake dry. Coarsely puree basil, pine nuts, garlic, parmesan and 4 tbsp. oil in a tall mixing bowl with a hand blender. Season to taste with salt, pepper and lemon juice.
Wash the fillets, dab dry and cut into 3 pieces. Season with a little salt and pepper. Wash sage, dab dry. Cut ham lengthwise in half. Cover the skin side of the fish pieces with sage and wrap with ham.
Clean and wash the vegetables. Peel the peppers with a peeler and quarter them lengthwise. Cut zucchini and aubergine into slices, salt lightly and leave to stand for about 10 minutes.
For the puree, peel, wash and quarter the potatoes, cover and cook in salted water for about 20 minutes.
Dab the vegetables with salt and water with kitchen paper. Heat 2 tablespoons of oil in a large frying pan. Fry all vegetables for about 10 minutes, turning them over. Season with salt and pepper.
Heat 1 tablespoon of oil in a second pan. Fry the fish saltimbocca in it for about 3 minutes on each side.
Drain the potatoes. Heat milk and butter and add. Mash everything with a potato masher. Season to taste with salt and nutmeg. Stir in pesto loosely to taste. Serve everything.