Heat a large soup pan over a medium heat and add 1 tablespoon of olive oil (alternatively, substitute the oil with some water). Add in onions and sauté for 5 minutes until lightly browned on the edges.
Add in the remaining vegetables, along with the lentils, turmeric, cumin, ground coriander, salt and pepper, and grated ginger. Sauté for 1 minute and then pour in the vegetable stock.
Bring the soup to the boil then reduce the heat to a simmer. Simmer the soup uncovered for 18-20 minutes or until the vegetables have softened.
If the soup is too thick, add in a little more vegetable or water to loosen. Serve with a sprinkle of freshly chopped coriander.