For the vegetable sauce, peel and finely dice the onion. Clean, wash and chop the green pepper and tomatoes. Wash parsley and cut into fine strips. Put prepared ingredients, vinegar and sugar in a pot.
Season with salt and pepper. Mix everything well and let it simmer for about 30 minutes while stirring. Season to taste again, let cool down. Wash and chop the meat. Clean and wash the leek. Cut into slices of about 3 cm thickness and wrap each slice of bacon around it.
Clean and wash the red pepper and zucchini. Cut the bell peppers into pieces and the zucchini into slices. Put all ingredients alternately on skewers. Brush with oil and sprinkle with pepper. For the croissants take the dough out of the package.
Roll apart, divide into triangles. Sprinkle with 3 tablespoons of sunflower seeds and form into croissants. Spread with milk and sprinkle with remaining sunflower seeds. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 12 minutes.
Grill the skewers on the hot grill all around for about 10 minutes. Salt. Arrange skewers, croissants and sauce.