In a dry skillet over medium heat, toast the guajillo and pasilla chilies for about 2 minutes or until they become fragrant. Once toasted, transfer them to a bowl and soak in hot water for 20-30 minutes, or until they soften. Drain the chilies and place them in a blender.
To the blender with the softened chilies, add the chopped onion, minced garlic, ground cumin, dried oregano, and 1 cup of beef broth. Blend everything on high until a smooth paste forms, adding additional broth as necessary to achieve a pourable consistency.
In a large pot or Dutch oven, heat a drizzle of oil over medium-high heat. Season the beef chunks generously with salt and pepper. Sear the beef in the hot pot for about 5-7 minutes, turning occasionally, until nicely browned on all sides.
Pour the silky chili sauce over the browned beef and add the bay leaves along with the remaining beef broth. Stir to combine, cover the pot, and lower the heat to let it simmer gently for 2.5 to 3 hours, or until the beef is fork-tender and easily shreds.
Using a slotted spoon, transfer the beef from the pot to a cutting board. Shred the meat with two forks into bite-sized pieces. Once shredded, return the beef to the pot and stir to combine with the flavorful broth. Allow it to simmer for an additional 10-15 minutes to absorb even more delicious flavors.
In a separate skillet over medium heat, warm the corn tortillas, cooking each side for about 30 seconds until pliable. For an extra boost of flavor, briefly dip the warmed tortillas into the broth before assembling the tacos.
Take a generous portion of the savory meat mixture and place it onto each tortilla. Garnish with a sprinkle of chopped cilantro and diced onion for crunch.
Place the tacos on a serving platter and add lime wedges on the side for a zesty squeeze over the top before enjoying.
Notes
For added flavor, dip tortillas in broth before assembling.