serves 10 people
1/4 cup canola oil
4 lbs onions, sliced
4 cloves garlic, chopped
1/2 teaspoon salt
1/4 teaspoon white pepper
8 cups water, vegetable or chicken stock
3 large sweet potatoes cut in chunks
Heat oil in a large pot. Add onions and cook on medium to high heat, mixing often until onions are golden browned, but not burned. This takes about 30 minutes. When you think the onions are brown enough, cook another 3-5 minutes.
Add garlic, salt, and pepper and cook five minutes more. Add the sweet potatoes and water/stock. Bring to a boil and then simmer for 40 minutes until the potatoes are soft. Cool slightly.
Purée using an immersion blender or in batches in a blender or food processor until the soup is completely smooth. Taste for seasonings and add salt or white pepper as needed.