Stuffed Aubergines with Tomato&Mint sauce

Fried aubergines with tomato sauce are a typical meal for Southern Bulgaria ( I suppose for part of the Balkans also) and the recipe of stuffed aubergines I know from my grand-mother. However, this one is a variation of that recipe, using minced beef and fresh mint.

You need:
2 medium-sized aubergines
250 gr minced beef
1 large onion head
light soy sauce
a bunch of fresh mint
1 or 2 fresh green pepper
3-4 cloves of garlic
white pepper, 1/2 teaspoon of cumin
1 peeled tomato

butter

for the tomato sauce
oil
400 gr peeled tomatoes
fresh mint
1 onion head

What to do:
Cut the aubergines lengthwise. Leave them under salted water for 5-10 minutes and drain. Remove pulp from the middle of each piece of the aubergines using a knife and a spoon. Cut the middle in small parts and start frying in a pan on high heat. Cut the green pepper(s) finely and add them too. In a blender puree the first onion head with 4-5 sprigs of fresh mint and place it in the frying aubergines. Stir and add the minced beef and the spices. At the end add the peeled tomato. Remove from heat.
Place the aubergine halves in an oiled baking pan. Add pieces of butter on them and then stuff them with the beef and vegetables mixture. Bake on some 200 degrees until the aubergines are soft enough.
In the meanwhile puree in a blender another head of onion with 3-4 sprigs of mint. In a fry pan add oil and fry the mint and onion mixture and the peeled tomatoes, until the mixture thickens.