Preheat oven to 400F. Line a baking dish with parchment paper, if you like, to make cleanup easier. Place the onions in the dish and bake until soft all the way through. If you’re using a metal pan with no parchment, 45 minutes may be enough but for ceramic dishes, be prepared to add more time. Onions should be darkened on the outside and almost squishy.
Allow the onions to cool until they’re comfortable to handle. Peel onions and discard peel and any discolored parts. Place onion “innards” in a high-powered blender along with lemon juice and salt. Blend until silky smooth. Check flavor and add more lemon juice or salt if necessary.
Use to add creaminess and flavor to soups (such as tomato soup) and other dishes or as the base for salad dressings and sauces, like my Fat-Free Onion Ranch. Makes about 1 cup.
I used 4 onions that ranged from small (3 ounces) to medium (6 ounces). If your onions are different sizes as mine were, they will probably cook at different speeds so be prepared to take each one out as it becomes soft.You can increase the richness by blending in a few cashews, but then it's no longer fat-free.One serving is 2 tablespoons.Adapted from Food 52.