1. In a large saucepan, heat the oil over medium-high heat and fry the onion, salt, and pepper until the onions are translucent, about 5 minutes. Add the garlic and fry for another minute.
2. Add vegetable stock, carrots, rice (or potato) and bring to boil. Cover, reduce the heat and simmer until the carrots are tender, about 20 minutes.
3. Use an immersion blender to puree the soup until it is smooth.
4. If serving immediately, ladle into bowls and top with herbs and sour cream or garlic croutons.
5. Once cooled, the soup will keep in the fridge for a couple days or may be frozen in a freezer-safe container.

To make the croutons:

1. Preheat oven to 350F/175C.
2. Cut the bread into small cubes, about 3 cm thick.
3. Toss bread cubes with the olive oil and garlic, and place on a baking sheet.
4. Bake in oven for about 15 minutes, stirring them around about halfway and watching that they don’t burn. Set aside to cool.