Put buckwheat in a sieve, wash thoroughly and drain well. Clean the leek, cut it half lengthwise and wash thoroughly. Cut the leek into rings. Clean, wash and cut the peppers into pieces.
Heat 2 tablespoons of oil in a wide saucepan. Sauté leek and pepper pieces while turning for 2-3 minutes. Add buckwheat and sauté for about 2 minutes, turning. Add stock, bring to the boil, cover and cook over a low heat for 15-20 minutes until tender.
Meanwhile wash the salmon, dab dry and season with salt. Heat 1-2 tablespoons of oil in a coated frying pan. Fry salmon over medium heat while turning for 6-8 minutes. Remove and season with white pepper.
Stir the cream into the vegetable buckwheat, season with a little salt and pepper. Arrange the vegetable buckwheat and salmon fillet on plates. Garnish with dill if desired.