Lay poblano and jalapeño chilies in a single layer in a 10- by 15-inch pan. Broil 3 to 4 inches from heat, turning occasionally, until skins are blackened and blistered, 15 to 20 minutes. Let cool. Wearing gloves, pull off and discard skin, stems, veins, and seeds. Rinse chilies and chop coarsely.
In a 6- to 8-quart pan, combine chilies, tomatoes, onions, cilantro, lime juice, and salt to taste. Bring to a boil over high heat, then simmer 10 minutes.
Let salsa cool, then serve, chill airtight up to 3 days, or pack in easy-to-use portions in freezer containers and freeze up to 1 year.
Nutritional analysis per 1/4 cup.