Toast the sunflower seeds and set aside. Combine the mustard, vinegar and oil, season.
Halve the tomatoes and set aside. Thinly slice the radish.
Add the radish, mix and leave to steep for a moment.
Rinse the fish (inside and out) in cold water, pat dry, salt the inside.
Slice the shallot. Stuff each fish with the sliced shallot and 2 sprigs of tarragon.
Brush each trout with oil. Grill: Grill the trout over/on a medium heat (approx. 200 °C for approx. 7 mins. each side, season.
Plate up the salad
Stir in the bean sprouts and reserved tomatoes shortly before serving. Plate up the salad and scatter over the toasted seeds.