Step 1Heat an outdoor grill or an oiled grill pan.
Step 2Fry the pancetta in a large skillet over medium-high heat, stirring occasionally, until crispy, 10 minutes. Drain on paper towels and set aside.
Step 3Meanwhile, place the pineapple and mango in a large mixing bowl. Cut away the rind and pith from the orange and, cutting in between the membranes, remove the segments. Add to the bowl. Quarter the onion, remove any core, and slice as thinly as possible. Add to the bowl.
Step 4Brush the mahi-mahi filets on both sides with 1 tablespoon of olive oil, season with salt and pepper and the chili powder. Place the fish on the grill and cook until it flakes slightly with a fork and is opaque, 4 to 5 minutes per side.
Step 5Whisk together the seasoned rice vinegar, the remaining 1 1/2 teaspoons of olive oil, the orange juice, pepper to taste and the grated ginger. Add the snipped pieces of fresh mint and mix.
Step 6Pour the dressing over the fruit salad in the large bowl and mix. Mound the salad in a serving bowl lined with butter lettuce and garnish with the crispy pancetta. Serve the fish alongside with the lime slices for garnish.