Heat 1/2 tablespoon vegetable oil in a large pot over medium-high heat. Pat the beef dry and season with salt and pepper. Brown in batches, about 4 minutes, adding more oil as needed. Transfer to a plate.
Reduce the heat to medium and add 1 1/2 tablespoons oil to the pot. Add the onions and garlic; cook, stirring, until golden, about 6 minutes. Add 1/3 cup chili powder, the oregano and tomato paste; cook, stirring, 30 seconds.
Return the meat to the pot and stir in the tomatoes with their juices, broth, espresso and pinto beans. Bring to a boil, then reduce the heat and simmer, partially covered, until the beef is tender, about 2 hours.
Stir the remaining 2 tablespoons chili powder into the chili. Divide among bowls. Top with cheese, sour cream and/or avocado.
This base recipe is relatively tame; a last-minute hit of chili powder adds just a touch of heat.
Add 5 crumbled dried arbol chiles to the pot with the tomato paste, then continue as directed.
Add 5 crumbled dried arbol chiles with the tomato paste and continue as directed, omitting the beans. Stir in 1 cup chopped pickled jalapenos before serving.