Place a skillet (frying pan) over medium heat. Add the pancetta or bacon and allow to crisp, then turn over to crisp on the other side. Remove from the heat, set aside on a plate lined with paper towels, then snip into small pieces. Preheat the oven to 350°F.
Put the tomatoes into a baking dish, add the extra virgin olive oil, and turn to coat them. Sprinkle with the oregano and some salt and pepper. Bake in the oven for 45 minutes, or until just black at the edges. Remove from the oven. Reserve a few tomatoes for the garnish and put the rest into a blender and blend to a puree.
Place a medium pan over medium heat. Add 1 tablespoon of the olive oil, the onion and garlic, and cook for 2–3 minutes, or until translucent. Add the buckwheat and pour in the red wine. Allow the wine to be absorbed by the buckwheat, then add the tomato puree. Cook for 20 minutes, or until the puree has almost all been absorbed. Remove from the heat.
Stir in the Parmesan and divide the buckwheat between 2 plates. Top with the avocado, pancetta or bacon, and reserved tomatoes. Sprinkle with a little salt and pepper to serve.