Start by heating the olive oil in a large 5-quart pot over low heat. Add the chopped onion and sauté for about 5 to 7 minutes, stirring occasionally. Look for the onion to become soft and translucent, which will signal that it’s ready for the next step.
While the onion is cooking, take this time to slice the mushrooms. Once the onions are ready, add the sliced mushrooms to the pot and increase the heat to high. Stir them frequently for about 10 minutes, until all the liquid from the mushrooms has evaporated. You’ll notice they will shrink and become beautifully browned.
Next, prepare the potatoes and carrots. Peel them, then cube the potatoes and chop the carrots into bite-sized pieces. Add these vegetables to the pot, along with the rest of the ingredients, excluding the flour. Stir everything together thoroughly and bring the soup to a boil.
Once the soup reaches a boil, reduce the heat to medium. Allow it to simmer for about 1 hour. Keep an eye on it, as about one-third of the liquid will evaporate, which will concentrate the flavors even more. Stir occasionally to prevent anything from sticking to the bottom.
After an hour, it’s time to thicken the soup. In a small bowl, mix the flour with ½ a cup of cold water until there are no lumps. Gradually add this mixture to the soup while stirring continuously. Continue to cook for another 10 minutes, allowing the soup to thicken beautifully.
Once thickened, remove the pot from heat and let the soup cool down slightly. This will not only enhance the flavors but also make it more comfortable for serving.
