Heat barbecue to high. Pat the trout dry with paper towel and rub with 1 tbsp (15 mL) olive oil. Season with ¼ tsp (1 mL) salt and ⅛ tsp (0.5 mL) pepper. Sprinkle with the curry powder, patting it onto all sides of the trout. Set aside.
In a bowl, combine the yogourt, remaining olive oil, cucumber, basil, mint, lemon zest and juice and sugar with the remaining salt and pepper. Mix well.
Grill the trout with the lid closed for 4 to 5 min. or until just cooked through. Divide trout fillet into 4 pieces and plate topped with 2 tbsp (30 mL) yogourt sauce each.
No BBQ? On a greased, foil-lined baking sheet, broil fish in the middle of the oven for 5 to 6 min. or until cooked through.