Mexican bean soup with guacamole

Name: Mexican bean soup with guacamole
Prep time: 10 min
Cook time: 20 min
Total time: 30 min
Cuisine: Mexican
Ingredients: 2 tsp rapeseed oil; 1 large onion finely chopped; 1 red pepper cut into chunks; 2 garlic cloves chopped; 2 tsp mild chilli powder; 1 tsp ground coriander; 1 tsp ground cumin; 400g can chopped tomatoes; 400g can black beans; 1 tsp vegetable bouillon powder; 1 small avocado; handful chopped coriander; 1 lime juiced; ½ red chilli deseeded and finely chopped (optional)