Prep the slaw first. Finely shred the cabbage and add it to a medium bowl. Add the lime juice and salt, and massage them into the cabbage using your hands. This will help break down and soften the cabbage. Set aside while you cook the shrimp.
Chili Lime Shrimp Tacos
In a large bowl, season the shrimp with Tajin and sea salt. Toss together. Melt 4 tbsp of butter in a pan over medium-high heat. Add the shrimp and cook for 2-3 minutes on each side. Smaller shrimp will cook in 4 minutes, larger in 6 minutes.
Once shrimp is cooked, squeeze half lime over top and add 1/4 cup of cilantro. Toss well. If using shrimp with the peel on, carefully remove the peel and tail. Toss them back into the pan and toss again to coat the shrimp in all of the flavors.
Toast the tortillas in a pan or right on the stovetop. I like to get a little char on one side. This will take about one minute for each side.
Assemble the tacos: In a tortilla, add some slaw, 3 large shrimp, and top with pickled onions and cilantro. Finish with a squeeze of lime. Serve while hot.