Summer Squash Soup
Adapted from my original take on it, which was adapted from Gourmet


3 tablespoons olive oil
1 tablespoon butter
1 medium onion, halved lengthwise and thinly sliced
1/2 teaspoon salt plus more to taste
2 pounds yellow summer squash or zucchini, halved and thinly sliced
2 carrots, thinly sliced
1 sweet potato, peeled, halved and thinly sliced
4 cups low-sodium chicken stock
Freshly ground black pepper

Heat oil and butter in a large, heavy wide pot over moderate heat. Cook onion with salt, stirring until it begins to caramelize, about 8 minutes. Add remaining vegetables and stock and bring to a boil. Reduce to a simmer and cook, partially covered, until vegetables are very tender, about 20 minutes. Let cool for 10 minutes off heat before pureeing to desired consistency. Season with additional salt and pepper to taste.