01 In a 6-quart Instant Pot, stir together the beef, onion chunks, 1 teaspoon salt and ½ cup water. Lock the lid in place and move the pressure valve to Sealing. Select Pressure Cook or Manual; make sure the pressure level is set to High. Set the cooking time for 50 minutes.

02 While the beef cooks, in a 12-inch skillet over medium, toast the garlic and all of the chilies, turning occasionally with tongs, until the garlic is browned on all sides and the chilies are fragrant and just a shade darker, about 5 minutes. Transfer to a medium bowl. When cool enough to handle, break the chilies (or snip them with kitchen shears) into smaller pieces, discarding any remaining seeds, and add them to a blender. Add the boiling water, garlic, bay, cumin, oregano, allspice, thyme and ½ teaspoon salt. Puree, scraping the blender as needed, until smooth, about 1 minute; cover and refrigerate.

03 When pressure cooking is complete, let the pressure reduce naturally for 15 minutes, then release the remaining steam by moving the pressure valve to Venting. Press Cancel, then carefully open the pot. Using a slotted spoon, transfer the meat to a large bowl. Tilt the pot to pool the cooking liquid to one side and use a wide spoon to skim off and discard as much fat as possible (*See note) from the surface. Select More/High Sauté and bring the liquid to a boil. Cook, stirring occasionally, until reduced to about ½ cup, 25 to 30 minutes. Meanwhile, shred the beef.

04 Stir the chili puree and the shredded beef into the reduced cooking liquid. Bring to a simmer and cook, stirring occasionally, until the mixture begins to sizzle, 5 to 8 minutes. Press Cancel to turn off the pot. Using potholders, carefully remove the insert from the housing. Stir in the lime juice, then taste and season with salt and pepper.

05 To serve, put the avocados, sliced onion and lime wedges into small bowls. Transfer the birria to a serving bowl, then serve with warmed tortillas and garnishes for making tacos.