½lbserrano peppers(or any green hot chilli pepper)
½cuponions(cut in chunks)
1 bunch of cilantro
Place tomatoes and chilies in a pot, cover them with water and cook them until they are completely tender (about 10 minutes).
Take them out of the water and let everything cool down for about 10 minutes. Reserve the cooking water.
Place the garlic, half the cilantro (including the stems), half the chillies and a pinch of salt. Pour one cup of water and blend on high for half a minute.
Add the other half of the cilantro, onion, tomatillos and cooked chilies and blend until you get the desired consistency for your sauce.
Adjust salt to taste, transfer the sauce to a bowl or jar, depending how you’re going to store.
The amount of chilies is to taste, you can add less or even more, depending on how spicy you’d like your sauce.
If you don’t have onion or don’t want to use it, you can add a pinch of sugar to balance the sour taste of the sauce.
The first blending with the garlic and cilantro and chili peppers helps it to blend perfectly the garlic and not have small bites in the sauce (which many people don’t like), the second blend is to make the sauce of the desired consistency.
You can also prepare the sauce in a molcajete or mortar instead of the blender.