Dredge the trout fillets thoroughly in the flour, shaking off any excess.
Heat a generous drizzle of extra virgin olive oil in a large skillet. As soon as it begins to sizzle, add the garlic clove and sage leaves.
After a moment, place the trout fillets into the pan to sear.
Brown the fillets on one side first, then carefully flip them over to brown the other side.
Season with salt and pepper to taste and finish cooking through.
Remove the fillets from the skillet and transfer them to a plate lined with paper towels to drain.
Remove the garlic and sage from the skillet. Deglaze the pan with the white wine, let the alcohol evaporate, and stir in the freshly squeezed juice of half a lemon to form the sauce.
Plate the trout fillets, spoon the pan sauce over them, sprinkle with freshly chopped parsley, and serve immediately.