Submerge dried ancho and guajillo chiles in boiling water for 10-15 minutes until pliable. Drain, reserving some soaking liquid. Blend chiles with vinegar, pineapple juice, achiote paste, garlic, brown sugar, cumin, cinnamon, and salt until thick and smooth.

Slice pork shoulder into 1/2-inch thick sections and coat thoroughly with the marinade. Cover and refrigerate overnight.

Stack marinated pork slices onto 3-4 metal skewers. Sear meat 2-3 minutes per side on hot, greased grill grates, then transfer to a cooler section of the grill and roast at 350-400°F for 1 1/2 to 2 hours, rotating occasionally. Rest wrapped in foil for 20 minutes.

While meat roasts, peel and quarter the pineapple lengthwise. Grill pineapple quarters for 10-12 minutes and jalapeños and onion rounds for 5-8 minutes until charred. Chop into bite-sized pieces, combine with cilantro, lime juice, lime zest, and salt to make the relish.

Slice rested meat by running a knife down the skewer sides. Char corn tortillas 30 seconds per side on a cast iron or griddle. Layer meat and pineapple relish on tortillas and serve with lime wedges.