Place the vegetables in a pan without defrosting them. Fry over high heat for about 10 minutes. Stir several times. Coarsely crumble the feta cheese. Roll out the dough. Spread vegetables and cheese on top. Roll up with the help of the enclosed baking paper, press the seam.
Spread the puff pastry with whisked egg yolk. Place the roll of dough with baking paper on a baking tray. Cook in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 20 minutes. Dice onion and fry in hot oil.
Sweat flour in it. Add tomatoes, bring to the boil and simmer for 5-10 minutes. Puree the sauce. Season with salt and tabasco. Serve with the strudel.