Prick the chiles in several places using the tines of a fork, or use a small sharp knife to cut a small x at the tip of each. (This will help the marinade penetrate better.) Place in a large saucepan, cover with cold water, and bring back to a boil over high heat. Cook for 1 minute; at once drain in a colander and allow to cool to room temperature.

In a large, deep non-reactive skillet or sauté pan, heat the oil over medium-high heat until not quite smoking. Add the onions and garlic; cook for 2-3 minutes, stirring frequently. Add the oregano, thyme, marjoram, peppercorns, and bay leaves. Cook, stirring for 1 minute longer. Add the chiles, vinegar, and salt. Bring to a boil, stirring. Remove from the heat and let cool completely.

Transfer to storage containers, distributing the solids and liquid as equally as possible. (Glass jars, nonreactive storage bowls with tight-fitting lids, or leakproof zipper-fastened plastic bags are all good.) Refrigerate for at least 3 days to let the flavors develop. The pickled chiles will keep in the refrigerator, tightly covered, for up to 2 months.