Chef Donnie Masterton at Tacolab by Tacolicious, in San Miguel de Allende, likes to serve these with tacos. The secret ingredient here is Maggi Seasoning (called Jugo Maggi in Mexico), a intense, dark, soy-like concentrate derived from fermented wheat proteins. Created in Switzerland, the formulation changes from country to country to suit regional tastes; Mexico’s is thick and meaty-tasting.
Roll the chiles in your hands to release their oils. Toast in a heavy skillet over medium-high heat, covered, turning often, until blistered all over and starting to cook through, about 10 minutes.
Remove from heat and drizzle with oil, then Jugo Maggi.
*Find at Latino markets or in the international aisle of supermarkets.