Heat the oil in a large frying pan over a low heat. Add the garlic and cook for 10 minutes. Discard the garlic and increase the heat to high.
Pat the sole dry with kitchen paper, then turn in the seasoned flour to coat both sides. Gently lower into the hot oil and cook for 4–5 minutes on each side until golden (if your pan isn't large enough, cook individually and keep the cooked sole warm in a low oven while you cook the remaining fish). Remove to a warmed serving plate.
Pour the wine into the frying pan and cook, stirring well with a wooden spoon to loosen any sediment from the base of the pan, for 1 minute. Add the passata, sugar, oregano and capers and bring to the boil. Check the seasoning and add salt and pepper if necessary, then spoon the sauce over the fish. Serve immediately.