To make the vinaigrette, combine the garlic, lime juice, vinegar, cumin, paprika, and a pinch of salt in a small bowl. Let sit for 5 to 10 minutes. Whisk in 6 Tbs. of the olive oil. Taste with a leaf of lettuce and adjust the vinaigrette with more lime juice, vinegar, or salt if necessary. Set aside.
Put the shallot in a small bowl and cover with ice water. (The ice water crisps the shallot and helps remove some its hot and gassy flavor.) Set aside.
Warm a small sauté pan over medium heat and add 1 Tbs. of the olive oil and the pumpkin seeds. Fry the seeds, tossing or stirring frequently, until golden, about 3 minutes. Transfer to a plate lined with a paper towel and season with salt.
Cut the skirt steak into about 6-inch lengths and return it to the refrigerator until shortly before you are ready to cook it. (Because skirt steak is so thin, you want the beef cold to prevent it from overcooking before it browns.) Season the beef with salt and coarsely ground black pepper. Warm a large cast-iron skillet over high heat until very hot.
Add the remaining 2 tablespoons olive oil and place the beef in the pan without overlapping the strips. Cook until the beef is nicely browned, 2 to 3 minutes. Turn and cook on the opposite side until medium rare, 1 to 2 minutes more; time will vary depending on the thickness of the meat. (If necessary, reduce the heat to medium high to finish cooking thicker sections of the meat.) Transfer to a plate and let rest for about 5 minutes.
Cut the avocados in half lengthwise, remove the pits, and slice the flesh diagonally into about 1⁄4-inch slices. Set aside.
Drain the shallot. Put the salad greens in a large work bowl; sprinkle the shallot, carrots, and radishes on top and season with salt and pepper. Gently toss the salad with just enough vinaigrette to lightly coat the greens. Taste and add more salt if necessary. Add about half of the pumpkins seeds and toss once more. With a delicate hand, transfer the salad to a platter or individual serving plates, evenly distributing the seeds, carrots, and radishes that may have fallen to the bottom of the bowl. Then, using a large spoon and starting at the very edge of the avocado (where skin meets flesh), scoop the flesh out of the avocado in one swoop. Separate the avocado slices and tuck them here and there among the greens. (At this point, I like to season the avocado, as best I can, with salt.) Thinly slice the meat against the grain. Arrange the skirt steak on the side or in the salad. Drizzle any remaining vinaigrette on and around the salad, focusing on the avocado and beef. Sprinkle the Aleppo pepper (if using) and the remaining pumpkin seeds on top. Serve immediately.