Set the Jerusalem artichoke pieces aside in lemon water to prevent them from oxidizing and turning brown.
Place the vegetables in a pot and cover them completely with boiling water. Season with salt and pepper, then simmer over low heat for half an hour.
Bacon and service
While the vegetables are cooking, prepare the bacon. Cut it into strips about 1 cm wide.
Heat a small amount of oil in a skillet and add the bacon strips. Fry over medium-high heat, turning frequently. Once the bacon is golden brown, remove from the heat and keep warm (in an oven at 60°C) on paper towels.
Once the vegetables are cooked, add the crème fraîche and blend thoroughly until the mixture is smooth and creamy. Taste the result and adjust the seasoning to your liking.
Pour the soup into each bowl and top with a few strips of bacon. Drizzle with a little olive oil and serve piping hot!