Peel the pumpkin and cut it first into 10 cm sections, then into thin slices.
Dust the slices with flour.
Add enough olive oil to a medium frying pan so it is 1 cm deep. Place over a medium heat then fry the pumpkin slices until golden on both sides. Drain on absorbent kitchen paper.
In a ceramic dish, make layers of the pumpkin slices, interspersed with the sage leaves and rosemary needles.
Put the vinegar in a small pan along with the garlic and some salt and pepper. Briefly bring to the boil.
Pour the hot vinegar over the layers of pumpkin in the dish. Leave for a few hours for the flavours to combine before serving.