Scrub Jerusalem artichoke thoroughly under water. Pre-cook in a pot covered with water for about 15 minutes. Drain, drain well, peel if necessary and cut into approx. 2.5 cm wide pieces.
For the olive salsa, roughly chop all the olives. Peel and finely chop the onion. Wash parsley, shake dry and chop the leaves coarsely. Mix everything with chili flakes, 1 tbsp. oil and lemon juice. Season with salt and pepper.
Whisk eggs and milk in a bowl, season well with salt and pepper. Wash and drain the spinach. Drain paprika, drain well and chop roughly.
Preheat the oven grill. Heat 1 tablespoon of oil in a large ovenproof pan. Fry the Jerusalem artichokes for about 2 minutes, turning them over. Fry the bell peppers briefly. Add spinach and let it collapse in 1-2 minutes. Pour egg mixture over it and let it simmer at low heat for about 7 minutes. Spread goat's cheese in flakes on top. Place the pan under the hot oven grill and bake the frittata for about 3 minutes until golden brown. Sprinkle with lemon zests if desired and serve with olive salsa.