Slow cooker black bean stew - deliciously spicy

Ingredients

• 300 grams dried black beans
• 400 grams ground meat (beef or half-and-half)
• olive oil
• 2 onions
• 3 garlic cloves
• 4 carrots
• 3 celery stalks
• 1 teaspoon ground cumin
• 2 teaspoons ground coriander
• 60 ml strong coffee
• 1 tablespoon cocoa
• 400 grams canned tomatoes
• 1 bay leaf
• 300 ml beef broth
• salt and pepper to taste
• 2 spring onions
• 6 tablespoons crème fraîche (or sour cream)
• 2 avocados
• 600 grams rice