The other night I was experimenting with pasta. I had a few cloves of choped garlic and one choped dry tomato slowly frying in about 3 tablespoons of olive oil (aglio olio style). Next I put some tomato paste into the pan to fry off a bit at first and then I added about one ladle of pasta water, hoping that it would make this tomatoey, garlicky sauce. However, the sauce broke. The oil and tomato paste kept separating. The look of the sauce was compromised even though it tasted good. Any idea how to prevent this? How to make the sauce not to break?
I'd argue against @user110084's advice - you should never put cornstarch or xantham gum into fresh sauce. There's simply no need for it, not to mention it can compromise flavour.
Adding too much water is not really the problem here - adding too much oil is. Tomato sauce is not an emulsion sauce (e.g. mayonnaise, vinaigrette, etc.) so oil should be used in smaller quantities. Aglio Olio is an oil based sauce but I see why you may want to combine the 2 to create something new so here are some ideas:
- Fry the garlic and tomato in less oil at first.
- Fix/create an emulsion of oil, water, tomato paste before adding to the pan.
- If you need to thicken, add more tomato paste. You should be able to easily find tomato paste with no salt/seasoning added. (I typically use half to 1 tube (or 1-2 small tins if in the US).