Cook bulgar wheat according to pack instructions, and leave to cool. Make a dressing: whisk the lemon juice, garlic and olive oil together and season to taste.
Tip the bulgar wheat into a bowl, add the tomatoes, spring onions, parsley and mint. Pour the dressing in and stir to combine. Flake the trout into chunks –discarding skin and bone. Gently fold into the salad.
Mix the yogurt and dill together in a small bowl, adding enough water to give the consistency of pouring cream. Season to taste and serve alongside the salad to drizzle on top.