Roast sesame seeds in a pan without fat for 3-4 minutes, remove and let cool. Mix with 1 teaspoon sea salt. Cut the mango from the stone, peel and dice the flesh. Wash, clean and slice the strawberries.
Clean, wash and cut the salad into bite-sized pieces. Season vinegar with sea salt, pepper and sugar, fold in 5 tablespoons of oil. Wash the fish and pat dry. Heat 1 tablespoon of oil in a frying pan.
Fry the tuna steaks on each side, depending on their thickness, for 2-3 minutes, remove and season with sesame salt. Mix salad, strawberries, mango and vinaigrette, season with salt, pepper and sugar.
Arrange salad and tuna fish on plates.