In a medium saucepan, add oil and heat over medium heat. Add garlic cloves and roast until soft. Remove and add to blender or Vitamix.
In the same saucepan, add tomatillos, jalapenos, serrano peppers, and onion.
Cover with cold water and bring to a boil over medium high heat until soft and the color has changed to a pale green.
Remove tomatillos and continue boiling the peppers until pale green, if needed.
Drain water, reserving ⅓ cup.
Add the cooked ingredients, salt and reserved water. Blend until combined and smooth.
Lastly, add the avocados and cilantro. Blend until creamy and smooth.
Serve with your favorite chips or top tacos, burritos, beef, chicken or your favorite Mexican recipes.