Ingredients
Method
- Place a Dutch oven or large saucepan over medium heat and melt the butter.
- Add onion wedges, water, tomatoes with their juices, and half a teaspoon of salt.
- Bring the mixture to a simmer. Cook uncovered for approximately 40 minutes, stirring occasionally and seasoning with additional salt as needed.
- Blend the soup until it reaches your desired consistency, then season to taste. Use an immersion blender for ease or a standard blender in small, careful batches. When using a blender, do not fill it completely, as hot liquid expands. For safety, remove the blender lid's center cap and cover the opening with a folded kitchen towel to vent steam and prevent splatters.
Nutrition
Notes
Ingredient Swap: I often use a full can of tomatoes and a whole onion when I'm cooking for a family, and just add a splash more stock or water to get the right consistency.
Storage Tip: This soup keeps beautifully in the fridge for up to four days, and I find the flavors meld and deepen overnight, making it a fantastic make-ahead lunch.
Blending Safety: From personal, messy experience, please vent your blender lid with a towel over the hole.
The steam from hot soup creates serious pressure, and I've cleaned tomato puree off my ceiling more than once.
Common Mistake: Don't rush the simmer.
Giving the onions and tomatoes a full 40 minutes to break down is what builds that deep, sweet, caramelized flavor that makes this soup so special.
Serving Suggestion: My favorite way to serve this is with a generous swirl of good olive oil and a handful of torn fresh basil right at the end for a bright, fragrant finish.
Equipment Note: If you don't have a Dutch oven, a heavy-bottomed pot is essential here to prevent the butter from burning and to distribute the gentle heat evenly for that long simmer.