To prepare the tomatillos, peel back the husk from the smooth green tomatillo skin. Rinse the tomatillos with warm water and cut into quarters. (Canned tomatillo salsa can be used instead of fresh.)

Place the husked tomatillos, onion, chilies, garlic, and 1 teaspoon oil in the baking pan, stir well and transfer to the oven. Roast about 20 minutes until the tomatillos are soft and dark green. Set aside to cool.

Transfer the mixture to the blender; add the salt, lime juice, and cilantro. Purée.

Place the skillet on the stove over high heat and when it is hot, carefully add 2 teaspoons oil.

Put the tilapia fillets in the pan, waiting about 30 seconds between additions. Cook about 5 to 6 minutes, until golden brown on both sides.