I recently ate at a Mexican restaurant with a delicious sauce. They were willing to sell it to me if I put in a special order, but they insisted it was so easy to make that I should just make it myself instead. I know the ingredients are jalapenos, habaneros, onions, and garlic. There is no water or anything else, just those four ingredients. The end result is a yellowish green sauce with a smooth, almost paste consistency.
I think I can figure out cooking the ingredients and blending them together, but how do I even take a guess at the ratios? None of the flavors were overpowering (it didn't taste mostly like onions or jalapenos or garlic), so there's not an obvious base, but I doubt they're anywhere close to equal proportions either. I don't need the results to be an exact match, but I'd like it to at least resemble what I had in the restaurant.
What's the best approach to this?