Grilled Tortillas with Fresh Chiles and Pickled Red Onions

Tierra Vegetables, a farm near Healdsburg, California, grows all kinds of fresh chiles and also makes dried chiles and marvelous smoked chipotle chiles, all of which you can mail-order. They once served me this incredibly potent sandwich; it remains one of the most memorable things I have ever eaten—a paragon of simplicity and an explosion of flavor. It is not for the faint of heart.