Fill medium pot with water and bring to a boil over medium-high heat. Add in tomatillos and jalapenos. Cook for 10 minutes, until tomatillos and jalapenos have softened. Drain water and place tomatillos and jalapenos in a large blender. Add avocados, cilantro, garlic, onions and lime juice. Blend until smooth. Taste and season with salt. Serve immediately or transfer to an air-tight container to chill in the refrigerator.