Heat the olive oil and sautee the mushrooms, onion, and pepper for 4-5 min, stirring constantly. Add the garlic and continue sauteeing for 3-4min, stirring. Add the canned tomatoes, the vegetable stock cube, salt and pepper, and cook until the vegetables are soft.
Add the parsley and stir once more. Boil the orzo pasta and drain. Place it in an ovenproof dish, add the sauce and stir. Bake in the oven for 8-10 min. Garnish with the cherry tomatoes and serve