I've been trying to make a good salsa for a while now, trying to perfect a base that is excellent and that I can rely to make ever single week. It's not as easy as I thought it would be and I'm still not satisfied with any of the batches I've made but I'll share what I've learned here. Trying to put it all together still but here are some things that seem necessary
1) Roast everything until about 70% charred either under the broiler or in a skillet
2) Serranos are great peppers, so are habaneros, and jalapenos too of course
3) Chipotle peppers can help kick the flavor profile up a notch. Usually, 1-2 chipotle peppers will do. Maybe add a touch of the sauce too
4) Start with a teaspoon of salt, then add in tiny amounts until you reach the desired taste
5) Salt is super important to make a good salsa, but there's a fine line between too little and too much. Be careful to find the perfect medium
5) Lime juice is also super important like salt, but do not add too much. Again find the balance of what the batch needs
6) Finely chopped cilantro is important to boost flavor and depth
7) Chicken Boullion can help increase the taste. Buy a healthy one or make a substitute as most Chicken Bouillion products have terrible ingredients in them
8) Garlic is good, I almost always add one or two maybe three or so
9) A tiny pinch of sugar or good quality honey can help
10) Roasting everything w/ light olive oil rubbed onto the tomatoes, veggies, peppers can improve the flavor and blend or marry the flavors a bit better
11) Add a bit of cumin
12) Add a bit of oregano
13) Tomatillos have a great flavor profile, roasting one or two can help take the salsa to the next level