Gather up your ingredients.
Chop one onion, and measure out a half cup.
Clean and chop the white and pale green parts of the leek.
Peeling Jerusalem artichokes can be tricky due to their various knobs and ridges. Use a spoon to gently scrape off the skin and get in and out of the crevices.
Run each tuber under cool water to clean off debris. If there is skin left, you can continue scraping with the spoon to get it all off.
Heat 1/4 cup olive oil in a large pot, over medium high heat.
Add the leak and the onion. Sauté until soft, about 5 minutes.
Slice into smaller chunks.
Add the Jerusalem artichokes to the pot.
Add 5 cups of broth or water and a teaspoon of sea salt.
Bring to a boil.
Decrease the heat to a simmer. Cover and cook until the artichokes are tender. This should take about 25-30 minutes.
Meanwhile, you can prepare the crispy sage leaves. Hear 1 tablespoon of olive oil in a small sauté pan.
Drop in the sage leaves, and sauté until crisp, about 2 minutes.
Remove from the pan and drain on a paper towel.
Once the artichokes are tender, remove from the heat and let cool for a couple minutes. Working in batches, add to a blender and process until smooth.
Pour back into the large soup pot, and gently reheat to serve.
Garnish each serving with a couple crispy sage leaves. Drizzle truffle oil on top if desired.