Salsa (make in advance)
Mix all of the salsa ingredients in a bowl and chill.
Pat halibut fillet dry. Dust with sea salt and freshly ground black pepper. Squeeze the lemon over the top.
Spread 2 to 4 tablespoons of mayonnaise in a thin layer over the surface of the halibut.
Cook at 350° for 15 to 25 minutes, depending on the thickness of the filet. Top with salsa before serving.
Serve with Swiss chard fritters and a bowl of steaming jasmine rice.