Trim the aubergines, cut them in half lengthwise, then slice into half-moons about 1.5 cm / 1/2 inch thick. Toss with 1 1/2 tsp salt in a colander and leave it over the sink or a bowl for 30 minutes.

While they sit, slice the garlic thinly and chop the parsley. Rinse the aubergine slices under cold water to remove the extra salt, then pat them dry with a clean kitchen towel.

Heat 2 tbsp (30 ml) of the frying oil in a 30 cm / 12-inch deep skillet over medium-high heat for about 1 minute, until it shimmers. Add a third of the slices in a single layer and fry for 3 to 4 minutes per side, until golden brown. Move them to a plate, then repeat twice more with the remaining oil and slices.

Turn the heat down to medium-low and add 1 tbsp olive oil to the same skillet. Add the garlic and stir for 45 to 60 seconds, until fragrant and pale gold at the edges. If it starts to turn dark brown it will taste bitter, so lift the pan off the heat for a few seconds. Stir in the tomato paste for 30 seconds.

Pour in the tomatoes, water, vinegar, oregano, chili flakes if using, 1/2 tsp salt and the pepper. Simmer uncovered over medium heat for 8 minutes, until the sauce is thick enough to coat the back of a spoon.

Return the aubergines to the skillet and spoon the sauce over them. Cover, lower the heat, and simmer for 12 minutes, turning the slices gently once, until a knife slides in with no resistance. Stir in the parsley, then taste and add salt or a teaspoon more vinegar if needed. Serve warm or at room temperature.