In a large bowl mix scallions and ginger. Stir in peanut butter, hot pepper sauce if using, water, soy sauce and sesame oil. Taste for seasoning and adjust hot pepper sauce, if desired, to make sauce spicier. Stir until sauce is smooth.
Line a rimmed baking sheet with foil. In a nonreactive bowl, combine ginger, soy sauce, hot pepper sauce, orange juice, lemon juice and scallions. Toss to mix. Add salmon and stir to make sure it's well coated. Thread 3-4 cubes salmon on each skewer and place on baking sheet. Pour any remaining marinade over salmon.
Let salmon marinate while you heat the grill. Grill salmon 4-5 minutes on each side or until cooked through. Serve hot with lime wedges and Peanut Butter Sauce.
NOTE: Salmon may also be put under a broiler 4 inches from the heat source. Broil 4 minutes on each side.