Cut the pork chops into 1/2-inch thick strips and place them in a bowl or ziplock bag. Add the fajita seasoning, juice from 0.75 lime, and 1 tablespoon of vegetable oil. Toss everything together until the pork is evenly coated. Let it sit while you prepare the vegetables—this allows the seasoning to penetrate the meat and develop flavor.
Slice the green and red bell peppers into 1/4-inch thin strips, keeping them separate from the onion. Slice the yellow onion into similar-sized strips. Mince the garlic cloves finely and set aside. Having all your vegetables and aromatics prepped before cooking ensures the sautéing process stays on track and nothing overcooks.
Heat 1.5 tablespoons of vegetable oil in a large skillet over medium-high heat until it shimmers. Add the sliced peppers and onion, cooking for 3-4 minutes, stirring occasionally, until they have a light char and are tender-crisp. The vegetables should have some color but still maintain a slight crunch. Transfer them to a plate and set aside.
In the same skillet, maintain medium-high heat and add the seasoned pork strips from Step 1 in a single layer—work in batches if needed to avoid overcrowding. Cook for 2-3 minutes on the first side without moving them, allowing a light golden crust to form. Flip and cook the other side for another 1-2 minutes until the internal temperature reaches 145°F. I find that letting the pork sit undisturbed in the pan creates much better color and flavor than constantly stirring.
Reduce the heat to medium. Add the butter and minced garlic to the pan with the cooked pork, stirring constantly for about 1 minute until the garlic becomes fragrant and the butter melts into a light golden sauce. Squeeze the juice from the whole lime into the pan and stir to combine. Return the cooked vegetables from Step 3 to the skillet and toss everything together for 30 seconds to warm through and marry the flavors. I like to add the lime juice at the end rather than during cooking because it keeps the bright, fresh flavor from fading.
Taste the fajita mixture and adjust seasoning with ground cumin if desired—add it gradually, starting with 1/2 teaspoon and stirring well. Transfer to a serving platter and top generously with fresh cilantro. Serve immediately with warm flour or corn tortillas on the side so everyone can build their own fajita.