Heat 1 tbsp (15 mL) oil in each of two medium saucepans over medium heat. Add 1 cup (250 mL) onions to each pan; sauté until translucent, about 3 min. Add 1 tbsp (15 mL) garlic to each; cook for 1 to 2 min. Add carrots and ginger to one saucepan; beets to the other; cook, stirring, for a few minutes.
Add half a carton of broth and 1 1/2 cups (375 mL) water to each pan. Turn up heat to medium-high and simmer for 35 min. or until vegetables are soft.
Season both soups with thyme, salt and pepper. Working in batches, purée each soup separately, rinsing the blender or food processor in between to avoid colour transfer.
Return both purées to their saucepans and add balsamic vinegar to beet soup. Warm over low heat 5 to 10 min. or until soups thicken. Serve by filling each bowl with half beet and half carrot soup. Garnish each bowl with 1 tsp (5 mL) sour cream and 1/2 tsp (2 mL) pesto.