Use a large, sharp knife to trim away all the peel and pith from both grapefruits. Hold peeled fruit over a bowl and cut in-between the membranes to free the grapefruit segments; you should have about 1 cup. Squeeze the membranes over the bowl to extract the juice.
Place House-Autry Seafood Breader on a piece of waxed paper, House-Autry Yellow Plain Corn Meal on a piece of waxed paper and beaten egg/water mixture in a pie plate. Season trout fillets with salt and pepper. Lightly dust with breader, tapping off excess. Dip the fillets into the beaten egg, and then dredge them in the corn meal.
In a large skillet, melt 1 tbsp of the butter. Add the sage leaves and cook over moderate heat, turning once, until crisp, about 2 minutes per side. Transfer the sage leaves to a plate lined with paper towels to drain. Add ¼-inch of vegetable oil to the skillet and heat until shimmering. Carefully add trout fillets and fry over moderate high heat until golden brown and just cooked through (about 3 minutes per side). Divide the fillets among 4 plates.
Discard vegetable oil and wipe out skillet with paper towels. Add the fresh grapefruit juice and water to the skillet and bring to a boil; cook for 1 minute. Reduce the heat to moderate, add the grapefruit sections and simmer sauce for 1 minute. Remove skillet from heat and swirl in remaining 2 tbsp of butter, 1 tbsp at a time. Season with salt and pepper. Spoon sauce and grapefruit sections over the trout fillets. Garnish each fillet with 2 fried sage leaves and serve immediately
