Heat oven to 180°C/gas mark 4.
Put 250ml water into a pan with a sprinkle of salt and bring to the boil.
Add the buckwheat, cover with a lid and simmer gently on a low heat for 15-20 minutes (until it has absorbed all of the water and is tender).
In a large pan heat the olive oil and add the cubed aubergine. Cook stirring well for about 10 minutes.
Add the garlic, a sprinkle of chilli flakes (optional) and the oregano. Cook for another minute stirring.
Add the tinned tomatoes and tomato puree and bring to the boil.
Stir in the red wine vinegar, a good grind of black pepper and the cooked buckwheat.
Put into an ovenproof dish and lay the mozzarella over the top.
Bake for 25 minutes.