Peel carrots and garlic, cut carrots into small cubes, chop garlic finely. Wash and clean spring onions and cut them diagonally into slices. Heat the oil in a large pan, fry the carrots for about 5 minutes while stirring.
Add spring onions and garlic and steam briefly. Add 250 ml water, curry and 1 teaspoon salt, bring to the boil. Remove pan from heat, stir in couscous and let it swell for 2 minutes. Cut a lid off the tomatoes.
Carefully remove the flesh with a teaspoon. Pour the couscous filling into the tomatoes and place in an ovenproof dish. If necessary, place the lid on the tomatoes and sprinkle with a little sea salt.
Add 250 ml of stock. Cook in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: stage 2) for 10-15 minutes. In the meantime melt fat in a pot. Stir in the flour and sweat.
Add 200 ml stock and milk bit by bit while stirring and let simmer for 5 minutes. Wash the basil, dab dry and chop coarsely. Add to the sauce and puree with a hand blender. Season to taste with salt and pepper.
Serve the tomatoes with the sauce. Garnish with basil if desired.