Short rib "bourguignon" with spinach polenta

Name: Short rib "bourguignon" with spinach polenta
Prep time: 20 min
Cook time: 4 h
Total time: 4 h
Yield: 6 portions
Ingredients: 20 g extra virgin olive oil; 1 brown onion; 2 stalks celery; 2 garlic cloves; 1 bunch Dutch baby carrots; 50 g tomato paste; 10 g Beef stock paste; 2 dried bay leaves; 750 g red wine; 400 g canned chopped tomatoes; 2 pinches ground black pepper; 9 pickling onions; 2 tbsp extra virgin olive oil; 1800 g beef short ribs; sea salt; ground black pepper; 200 g pancetta; 200 g button mushrooms; 200 g polenta; 30 g unsalted butter; 120 g fresh baby spinach; 800 g water; 1 tsp sea salt; 1 tbsp extra virgin olive oil; 1 tbsp unsalted butter; fresh parsley; horseradish cream