Heat 2 tablespoons of oil in a large frying pan. Fry 6 roasting sticks in it for 4-5 minutes, turning them brown, take them out and let them drip off on kitchen paper. Fry the rest of the pieces in 2 tbsp. oil, remove.
##Wash and dry basil, pluck basil leaves from the stalks and cut into strips except for a little garnish. Peel onion and chop finely. Wash tomatoes and pat dry.
Add 1 tablespoon of oil to the hot frying fat of the Rösti. Fry the onion and tomatoes while turning them until the tomatoes start to burst. Stir basil strips, except for a little bit for sprinkling, into the ##vegetables##, season with salt, pepper and sugar.
Layer the tomatoes and roast chunks in an ovenproof dish. Crumble the feta cheese, mix with sour cream until smooth and spread on the casserole. Bake in a preheated oven (electric range: 225 °C/ convection oven: 200 °C/ gas: level 4) for approx. 10 minutes.
Remove the casserole, sprinkle with basil strips and garnish with leaves.