First, add the tomatillos, jalapeno, onion, cilantro, lime juice, and salt to a blender. Blend on low speed, adding cold water a little at a time as needed, until the consistency is smooth yet slightly thick. Note that you may not need to use the entire amount of cold water called for - use your best judgment and only add enough to ensure a smooth consistency.
Next, heat vegetable oil and garlic in a small saucepan over medium heat until garlic is fragrant, about 1 minute.
Transfer the sauce from the blender to the saucepan and stir to combine. Cook until the sauce has darkened in color and the flavor is tart, about 8 to 10 minutes.
Remove from heat and serve over burritos, enchiladas, or nachos, or let cool and store in the fridge for up to 1 week.
Notes
Serving suggestions: Mexican verde sauce is so versatile, it can be used in many different dishes. Here are a few suggestions: