Crab Balls with Grapefruit Salad

Name: Crab Balls with Grapefruit Salad
Ingredients: 1 tablespoon unsalted butter; 2 tablespoons minced onion; 2 tablespoons cornstarch; 1/2 cup unsweetened coconut milk; 1/2 pound lump or peekytoe crabmeat, picked over and lightly shredded; Salt; 1 cup panko; 1 1/2 tablespoons mixed white and black sesame seeds; 2 large egg whites, lightly beaten; Vegetable oil, for frying; 1/4 cup plus 2 tablespoons sugar; 2 tablespoons fresh lemon juice; 2 tablespoons finely grated fresh ginger; 2 pink grapefruits; 1 green Thai chile, minced; 1 tablespoon soy sauce