Preheat oven to 450 degrees.
Line a baking sheet with parchment paper or aluminum foil.
Remove the husks from the tomatillos and rinse to remove the stickiness on the outside.
Pat dry with paper towels
Remove the stems from the jalapeno peppers then rinse and dry.
Take a small square of foil, add the garlic cloves, a small drizzle of oil and seal them into a small packet.
Add the tomatillos, jalapenos and onion to the baking sheet. Drizzle with oil, sprinkle ¼ teaspoon of salt and use your hands to toss it all together making sure to evenly cover everything with oil.
Add the packet of garlic to the baking sheet.
Place the baking sheet in the oven and roast for 10-15 minutes or until lightly browned exterior of the tomatillos and they are blistered and shriveling. (If you over-roast, just pour the juices from the pan into the food processor, no harm!)
Once roasted, allow to cool.
Place the roasted vegetables, oil, lime juice, cilantro, salt, garlic, pepper and cumin in a food processor and blend until you reach your desired consistency. Season with additional salt to taste and serve.
Store extra salsa in a sealed container in the refrigerator for 3-5 days.