Stewed Black Beans with Avocado Sour Cream and Chopped Tomatoes

Ingredients

• 500g dried black beans
• 1750 ml vegetable stock
• 1 red bell pepper - cored, deseeded & chopped
• 1 yellow bell pepper - cored, deseeded & chopped
• 4 garlic cloves, minced
• sprig of thyme
• 1 generous teaspoon ground cumin
• good pinch of cayenne pepper
• good pinch of ground mace
• salt
• 2 ripe avocado
• 1 - 2 limes
• 1 shallot, diced
• 2 ripe tomatoes, deseeded and chopped
• pinch of salt