Eggplant stuffed with buckwheat, feta, tomato

Ingredients

• 60 g whole grain buckwheat groats
• 4 large tomatoes
• 500 g tomato passata (sauce)
• 1/2 tsp oregano (dried or fresh)
• 2 tbsp olive oil
• 4 large eggplants
• 1 tbsp balsamic vinegar
• 1/2 tsp harissa (optional)
• 1 handful of chopped parsley
• 1 chopped clove of garlic
• 1 tsp tahini (optional)
• 20 g feta cheese
• 40 g breadcrumbs (gluten free if you are intolerant)
• 20 g freshly grated parmesan cheese
• 100 g greek yogurt (or plain yogurt)