I have a gas hob and metal-bottomed pots. The support for the hob is made of metal and is coated in black plastic, like the image below.  The previous owner has worn away at the layer of plastic that allows pots to move freely and quietly, so the metal is exposed.  The problem I'm trying to solve is that skillets and pots squeak horribly when they are moved due to the metal-on-metal scraping.     One option is to replace the support, but this seems wasteful and it will crop up again; Another option would be to heat the metal and use a plastic dip; in school we used a heat-and-dip treatment to treat metal products to give them this nice finish, but I don't have the equipment.   How can I mitigate this noise?  Is there a nice way to completely stop it?   
I've only made Aji de Gallina a couple of times and this was several years back. So, I searched through several recipes to get an idea of what some of the variations may be.  Across the board, I couldn't see how the peppers alone could impart that much color, given the total volume of the recipe. Especially the lighter yellow peppers.   As your dish tasted great, I don't think you are doing anything wrong.  So, here are a few ideas:   As you noted in your question, turmeric is an option. Most recipes call for such a small amount that it probably wouldn't affect the taste too much. You may get more color by substituting Aji Amarillo paste for part of all of the peppers. Most that I've seen have a very nice color. I used this when I made Aji de Gallina as the peppers were not available at that time. Here's one example:      Annatto (achiote) paste, powder, or seeds may be incorporated as it also gives a nice color. I haven't tried it with this dish but, as with other things, I would only use a small amount so as to not alter the flavor too much. Last, but not least, is my go to. I've kept a bottle of Amarillo yellow coloring in my pantry for years. Any time I have the flavor on point, but need the color, that's where it comes from. It takes a very small amount (think pinch) and does not change the flavor of your dish. Works great for rice, paella, sauces, etc. And, because it's also sold to foodservice, it's quite feasible that restaurants use it.    