1. Using a paring knife or chef?s knife, cut ends from lemons. Working from top to bottom, cut off peel, pith, and membrane in one motion, following curve of lemon. Hold lemon over a bowl to catch juice. Work knife in toward center along segments as close to membranes as possible, letting segments drop into the bowl. Squeeze juice from membranes into bowl. Coarsely chop segments.

2. Using a serrated knife, cut bread into 1/4-inch dice. Melt 1 tablespoon butter in a large nonstick skillet over medium-high heat. Add bread. Cook, stirring occasionally, until golden brown, about 4 minutes. Transfer croutons to paper towels to drain. Wipe out skillet; set aside.

3. Season trout with salt and pepper. Dredge in flour; shake off excess. Heat 2 tablespoons butter and 1 tablespoon oil in skillet over medium-high heat until butter has melted and oil is hot. Add 2 fillets; cook, turning once, until golden, 1 1/2 to 2 minutes per side. Transfer to a serving plate. Wipe out skillet. Add 2 tablespoons butter and remaining tablespoon oil; repeat with remaining fish.

4. Add remaining 2 tablespoons butter to skillet. Cook over medium-high heat until butter begins to turn brown, about 1 minute. Quickly remove from heat, and add capers, parsley, and lemon segments; swirl skillet to combine. Pour sauce over trout fillets, dividing evenly. Sprinkle with croutons. Garnish with lemon wedges and parsley.