To prepare the fennel remove the stalks but keep the fronds and set aside. Then slice the
bulbs to use. The fronts will be used to top up the final soup with.
Heat the olive oil in a large pot, sauté the sliced onion and fennel on a medium heat. Once
they soften then add the water in the pot.
Bring the water to a boil and add all the ingredients except from the tortellini. Cook on a
medium heat for 30min and then blitz them with an immersion blender.
Bring to a boil again, add the tortellini and let them cook for just a bit less than the recommended product time. Then take the pot off the heat and let the soup rest
for 5min or so before serving. This will help the soup thicken even more and
the tortellini will continue cooking.