The phrase "fresh tomatillos" refers to fresh, unripe green tomatoes that are commonly used in Mexican cuisine to prepare dishes like salsa verde. Full definition
Traditionally, this salsa is made with fresh tomatillos which are char grilled, then blended with the remaining ingredients to form a runny sauce. (sammyandbella.com)
Look for fresh tomatillos in the late summer and early fall farm markets. (vegkitchen.com)
If you can't find fresh tomatillos, substitute 1 cup green enchilada sauce. (vegetariantimes.com)