Heat the oil in a saucepan and saute the capsicum for 2 minutes. Add carrots, potatoes, salt and pepper. Fry 2-3 minutes. Add tarragon, water and stock cube. Bring to a simmer.
Cover and cook over medium heat about 20 minutes, until vegetables are tender. Add more water if necessary.
Remove from heat, puree with a hand blender and serve immediately.