Cover and bring about 2 liters of salted water to the boil in a saucepan.
Wash and quarter the tomatoes. Halve, peel and finely dice the onion.
Cook the ribbon noodles in boiling salted water for approx. 6 - 7 minutes until al dente. Then drain the pasta in a sieve and let it drain briefly.
Heat the oil in a high pan on medium to high heat and sweat the onion in it for approx. 2 - 3 minutes until colorless. Then add the cut tomatoes to the pan and fry everything for another 2 minutes. Deglaze the sauce with the stock and cream and season with salt, pepper, thyme and sugar.
In the meantime, remove the skin from the salmon if necessary. Cut the salmon into cubes, season with salt and pepper, drizzle with the lime juice and add to the tomato sauce. Cook everything for about 7-10 minutes, until the salmon is through and the sauce is creamy. Season everything with salt and pepper if necessary.
Spread the ribbon noodle on the plates, pour the sauce over them and serve.