Season the roast

• Preheat the oven to 165 °C (325 °F).
• Season the chuck roast generously on both sides with salt, pepper and taco seasoning.

Bake the roast

• Place the roast in a baking dish and cover with foil or a lid.
• Bake for about 1 hour per pound of meat, until fork tender.

Shred the meat

• Remove the roast from the oven and shred it into large chunks with two forks.
• If it does not pull apart easily, return it to the oven for 30 min.

Crisp the shredded beef

• Raise the oven temperature to 220 °C (425 °F).
• Toss the shredded pieces in the rendered fat and return to the dish, uncovered.
• Bake until the ends are nicely crispy.

Make the guacamole

• Mash the avocados and combine with the lime juice, orange juice, salt and pepper.
• Taste and add more lime juice and salt if needed.
• Stir in the chopped red onion and cilantro.

Warm the tortillas

• Warm the tortillas over an open flame until lightly charred, or use your preferred method.

Assemble and serve

• Spread a layer of guacamole on each tortilla.
• Add the crispy chuck roast, then top with chopped onion, cilantro and salsa macha.