Bring 4 cups of water to boil and add rice and 2 teaspoons salt to the water. Return to a boil, reduce heat, cover and let cook without removing cover, for 20 minutes. Remove from heat and let rest for 5 minutes.
While the rice is cooking, heat 1 tablespoon of the oil over medium-high heat in a large saute pan and saute the onion until it begins to turn translucent. Season salmon fillets with salt and pepper and sear each side, beginning the skin side first, leaving each side undisturbed for the first 2 minutes or so to allow the flavors to integrate into the surface of the fish and for the caramelization process to begin. Cook further until the fish flakes, approximately another 6 to 8 minutes, remove from heat and let rest.
Heat oil in deep fryer to 375 degrees F or according to the manufacturer's directions for similar food.
Mix rice, crab boil seasoning, mayonnaise, parsley and lemon juice. Fold in flaked salmon and form into 3/4-inch diameter "cocktail size" balls.
To make tempura, mix flour, cornstarch, baking powder, chopped chives in a bowl and add seltzer in a stream while whisking constantly. Season with salt and pepper. Place salmon balls on a slotted spoon and, holding over the bowl, ladle some tempura batter over each. Transfer to the deep-fryer basket and fry until golden.
Combine all the Dipping Sauce ingredients and serve with the fritters.