Here’s the simple magic: for every one tablespoon of tomato paste, you want about half a cup of water. That’s the baseline for a basic, pourable sauce. But we’re not making boring sauce—we’re making dinner.
If you want a thicker, more robust sauce (for pizza or dipping crusty bread), use less water. If you’re going for a loose, soupy sauce (hello, pasta), add a little more. It’s like Goldilocks, but with tomatoes.