Bring 1,250 ml vegetable stock to a boil. Stir in the couscous, remove from the heat and cover and leave to soak for about 10 minutes.
Halve the peppers, remove the core and partitions, wash and dry. Brush the inside and outside with olive oil.
Chop the sheep's cheese into small cubes. Fluff the couscous with a fork and place in a bowl. Add the sheep's cheese and season to taste with salt, pepper and lemon juice. Fill the peppers with it, place in an ovenproof, greased dish and pour in the rest of the broth.
Cook in the oven (middle rack, convection: 160 ° degrees) for 35-40 minutes. Garnish the stuffed peppers with parsley and serve.