Bring 2-3 l salted water (1 teaspoon salt per litre) to the boil. Clean, wash and quarter the courgettes lengthwise. Scrape out seeds with a teaspoon. Cut the zucchini into approx. 1⁄2 cm thick pieces. Peel onion and cut into fine strips.
Wash oregano, shake dry and pluck leaves from the stalks. Grate cheese finely.
Cook the pasta in boiling salted water according to the instructions on the packet. In the meantime heat the oil in a large pan. Sauté the zucchini and onion in it over medium heat for about 4 minutes. Pluck the trout into large pieces.
Add oregano to the zucchini mix in the pan and fry for about 2 minutes.
Whisk eggs, milk and cheese, up to approx. 2 tablespoons, season with salt and pepper. Remove approx. 4 tablespoons of cooking water. Drain noodles. Take the pan off the stove. Add noodles and cooking water. Stir the egg milk quickly into the hot noodles.
Serve the pasta and sprinkle with the rest of the cheese.
Tip 1: Important: Do not quench the pasta after pouring. Otherwise you will rinse off the starch and the sauce will not stick as well. For the same reason, do not add oil to the pasta cooking water! Tip 2: This carbonara does not only taste good with trout, you can also use other smoked fish.
Thus, smoked mackerel, halibut or stremel salmon also give a nice hearty aroma.