Prepare an ice bath to readily cool your salsa, and set aside. In a medium sized pot, combine jalapeños, serranos, onions, tomatillos, and garlic. Cover with water and bring to a boil. Continue cooking until tomatillos are softened.
Drain and place in a blender with lime juice, cilantro, oil, both vinegars, sugar, and salt. Puree until smooth. Immediately chill in ice bath to prevent browning. Store in refrigerator until ready to use.