Heat a large skillet over high heat for 2 minutes. Add the Guajillo Chile (2) and toast for 15 seconds on each side.
Add Onion (1/2) and Garlic (5 clove), cook, until slightly charred, about 3 minutes each side.
In a blender add the guajillo, onion, garlic, Dried Oregano (1 teaspoon), Bay Leaf (2), Kosher Salt (3 teaspoon), Ground Black Pepper (1 1/2 teaspoon), Ground Cumin (2 teaspoon), Distilled White Vinegar (1/2 cup), and Water (1 cup). Blitz on high for 1 minute.
Add Boneless Chuck Roast (2 pound), Water (2 cup), and marinade to the instant pot. Cover, and cook on pressure cook high for 90 minutes.
After the steam has been released, remove meat and shred with two forks. Optional: Boil the leftover broth until it has reduced to 1-2 cups, about 30 minutes. Use it as a sauce to serve with your tacos.
Serve barbacoa with Yellow Corn Tortilla (16) and garnish with Avocado (2), Fresh Cilantro (1/2 bunch), and Onion (1/2).