Step 1

Whisk together all of the spice rub ingredients in a small bowl; set aside.

Step 2

Pat beef pieces dry with paper towels then liberally season with the spice rub, gently pressing to adhere. Save any excess spices to add to the pot later.

Step 3

Heat 1 ½ tablespoons vegetable oil in a large cast iron skillet (or large Dutch oven for oven/stovetop method) over medium-high heat. Once very hot, add cubed beef and sear on all sides.

Step 4

Transfer beef to a 6 quart (or larger) slow cooker along with all remaining ingredients, including any leftover spices. Stir to combine. Cover and cook on HIGH for 3 ½ – 4 ½ hours or on LOW for 6-8 hours, OR until the beef shreds easily with two forks.

Step 5

Meanwhile, make Cilantro Lime Ranch (if using), by whisking all of the ingredients together. Refrigerate until ready to serve.

Step 6

Remove the beef to a rimmed plate or large bowl (do NOT discard juices in slow cooker), and shred with two forks, discarding any excess fat.

Step 7

Add the shredded beef back to slow cooker and toss with slow cooker juices. Cook on low for 20 minutes for beef to absorb juices. Taste and season with hot sauce/cayenne pepper, lime juice or brown sugar to taste.

Step 8

Remove beef with a pair of tongs to a serving bowl or strain in colander so tacos don’t get soggy. I like to save the liquid to cook my rice in (just add liquid plus water needed for rice).

Step 9

A little before making the tacos, preheat oven to 425 degrees F.

Step 10

Place tortillas between two damp paper towels and microwave for 30-60 seconds, or until pliable. Working in 2 batches (because the tortillas won’t all fit open faced on the baking sheet at once), lightly brush the top of the tortillas with olive oil then flip over (the oiled side should now be face down, touching the baking sheet so it gets crispy).

Step 11

Add a layer of cheese to the bottom half of the tortilla and top it with shredded beef (about 1/3 cup of each, give or take). Make sure to drain the beef well so it doesn’t make the tacos soggy. Fold the tortillas over in half and lightly press so they stay folded, you may need to flip the whole taco over so it stays. Repeat with remaining tortillas.

Step 12

Bake at 425 degrees for 8 minutes, flip the tacos over and bake an additional 5-8 minutes, or until the cheese is melted and the tacos are crispy.

Step 13

Stuff with desired toppings and dig in!