How do I recreate a restaurant's sauce if I know the ingredients but not the ratios? 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?
First, ask if they cook any of the ingredients. 

It's likely that they are all raw. 

Next, I would probably start with a mix with an approximate base that has the same color as the original sauce ( e.g. 1:1:1 with one clove of garlic). 

Save some of it on the side to use again, then add some of each ingredient to your base. 2:1:1:1 / 1:2:1:1 / 1:1:2:1 etc. 

Then taste each one, and that should give you some idea of how to tweak it next.