Lightly grease the inside of your crockpot to prevent sticking. Place the chicken breasts directly into the pot. In a small bowl, combine the taco seasoning and ground cumin together—I find mixing the spices first ensures even distribution throughout the chicken rather than having dry pockets of seasoning. Sprinkle this mixture evenly over the chicken.

Pour the diced tomatoes with green chilies and lime juice over the seasoned chicken. The liquid will create steam that cooks the chicken gently and evenly while infusing it with flavor. Cover and cook on high for 3-4 hours or on low for 7-8 hours, depending on your schedule. The chicken is done when it's tender and easily pulls apart with a fork.

Once the chicken is fully cooked, carefully remove it from the crockpot and set aside on a cutting board. Pour out most of the cooking liquid, leaving about half a cup in the pot—this residual liquid will keep your shredded chicken moist and flavorful rather than dry. Using two forks, shred the chicken into bite-sized pieces, then return it to the crockpot and stir to combine with the remaining liquid and tomato mixture.

While the chicken finishes, warm your tortillas using your preferred method—either directly over a gas flame for 10-15 seconds per side for a slight char, in a dry skillet for about 30 seconds per side, or wrapped in a damp towel in the microwave for 1-2 minutes. I like to char them lightly because it brings out their natural corn flavor and gives the tacos more character. Set up a taco bar with the shredded chicken from Step 3, warmed tortillas, and all your toppings so everyone can build their own.

Let each person build their tacos to their preference. Arrange the pico de gallo, guacamole, sour cream, fresh cilantro, lime wedges, and cheese on the table so guests can customize. A squeeze of fresh lime juice over the top brightens all the flavors and ties everything together.