Ingredients
4 Tbsp unsalted butter
½ large onion, cut into large wedges
1 (28-ounce) can tomatoes, whole peeled or crushed
1½ cups water, low sodium vegetable stock, or chicken stock
½ tsp fine sea salt, or more to taste
Directions
Melt butter over medium heat in a Dutch oven or large saucepan.
Add onion, water or stock, tomatoes, and salt. Bring to a simmer and cook uncovered for about 40 minutes. Stir occasionally and add additional salt as needed.
Blend until smooth with an immersion blender then season to taste. Serve.