Preheat oven to 400°F.
Remove the husks from the tomatillos. Rinse tomatillos under cold water and slice in half.
Place tomatillas on a parchment-lined baking sheet with onion, jalapeño and garlic. Roast for 20 minutes.
Add roasted vegetables to a blender or food processor and add cilantro, lime juice and Celtic Sea Salt. Blend until you reach desired consistency. (Taste and add additional salt, if necessary.)