Baked onions with nut stuffing

4 large onions, each weighing 225-275 g
150 g long grain rice
50 g hazelnuts
50 g salted peanuts
225 g tomatoes, roughly chopped
110 g cheddar cheese, grated
1/2 teaspoon dried basil
1/4 teaspoon dried oregano
1 teaspoon turmeric

1. Preheat oven to 200 C or 400 F.
2. Boil the onions in their skins for 45-50 minutes until very tender. Drain and leave to cool.
3. Cook the rice in plenty of boiling water, until tender. Drain well.
4. Put the hazelnuts and peanuts on a sheet of foil and cook under the grill until brown, turning frequently. Leave the skins on the hazelnuts and finely chop with the peanuts.
5. Mix the tomatoes with the rice, cheese, nuts, herbs and turmeric.
6. Slice off the tip and root of each onion, but leave on the coloured outer skin. Down one side of each onion cut through to the centre from tip to root. Ease the onions open.
7. Divide the stuffing between each onion, pressing it well into the centre. Place in a roasting tin, cover and bake for about 40 minutes. Serve hot.