Heat olive oil in a large skillet over medium-high heat until it shimmers—about two minutes. I actually sear the diced chicken in batches here because crowding the pan drops the temperature, and you lose that browning effect that adds flavor. Work in two batches, searing each side until golden, then transfer to your slow cooker.

In that same skillet, add diced onion and minced garlic to the remaining oil and cook for two minutes until fragrant. This is where that tomato paste goes—stir it in for another minute to let it caramelize slightly. Don't skip this step because you're building a flavor foundation that makes the whole dish taste intentional.

Add ground cumin, chili powder, and smoked paprika to the onion mixture and stir constantly for thirty seconds. This blooms the spices, releasing their essential oils so they're not just floating around in liquid. You'll smell the difference immediately—that's your signal to move forward.

Pour the chicken broth and salsa roja into the skillet, scraping the bottom with a wooden spoon to release any browned bits. Transfer this entire mixture to the slow cooker with the chicken, stirring everything together. Cook on low for 4 hours—don't peek constantly because every time you lift the lid, you add fifteen minutes to the actual cook time.

After four hours, the chicken should shred easily with two forks—if it still feels firm, give it another thirty minutes. Shred it directly in the slow cooker and stir to combine with all the juices. Taste and adjust salt or heat level now because this is your last chance before serving.

Warm your tortillas in a dry skillet or directly over a gas flame for about twenty seconds per side until they're pliable. This prevents them from cracking when you fill them, and it brings out the corn flavor. I learned this the hard way after years of wrestling with cold, brittle tortillas.