Put the skewers in water. Wash, clean and finely grate the cucumber. Peel garlic and chop finely. Mix yoghurt, sour cream and half the garlic. Mix in cucumber and season with salt and pepper.
Peel and finely dice the onions and mix with the remaining garlic. Clean, wash and cut the peppers into rings. Crumble cheese. Wash thyme, shake dry and, except for something to garnish, pluck leaves from the stems.
Wash, clean and slice the tomatoes. Put the tomatoes in the aluminium bowls. Spread cheese, pepper rings, onion-garlic mixture and thyme evenly on top. Season with salt, pepper and chili flakes.
Drizzle with oil and grill for about 20 minutes. Peel the skin from the sausage. Halve the sausage lengthwise. Remove skewers from water and let them drain briefly. Put 2 sausage halves crosswise on 2 skewers each. Grill the sausage skewers on each side for 2-3 minutes.
Arrange grilled vegetables and sausage together. Garnish with thyme. Add tzatziki.