Daube de boeuf à la Provençale

Name: Daube de boeuf à la Provençale
Ingredients: 1 kilo of beef stewing meat; 600 ml beef stock; 400 gram chestnut mushrooms; 3 carrots; 3 garlic cloves; 3 small red onions; 1 chili pepper; 1 can of tomato paste (140 gram); about 150 ml red wine; olive oil; pepper and salt to taste; 2 tablespoons Dijon mustard; large handful of black olives; 2 tablespoons paprika powder; 2 tablespoons all-purpose flour; 2 bay leaves; few sprigs of thyme; about 2 tablespoons herbes de Provence; about 30 gram dark chocolate; mashed potatoes or rice for serving