Preheat a grill to medium
Chop sweet potato and mango flesh into long wedges at least 1.5cm thick and place in separate dishes.
Combine the dressing ingredients (oil, mint, lime, vinegar & sugar) in a bowl and pour half over the mango and potato wedges.
With tongs, arrange sweet potato wedges under the grill and cook for 6-7 minutes until they start to soften. Turn and grill for another 6-7 minutes. While this side is cooking, arrange mango wedges under grill and cook for 2-3 minutes on each side.
Transfer all the wedges to a cutting board and cut into cubes. Toss into the remaining dressing.Toss lettuce, mint, potato and mango in a salad bowl and sprinkle a pinch of sea salt over to serve.