In a large bowl, combine the lime juice, ginger, 1 tablespoon of the oil, and ¼ teaspoon each salt and pepper.
Add the snap peas, onion, and sesame seeds, if desired, and toss to coat.
Heat the remaining tablespoon of oil in a large nonstick skillet over medium-high heat.
Season the fish with ½ teaspoon salt and ¼ teaspoon pepper. Cook until opaque throughout, 3 to 5 minutes per side.
Serve with the salad and lime wedges.