In a large aluminum pan, coat pork shoulder with 1/2 of the reserved Red Curry Salsa. Place in fridge and marinate for 2 hours.
Cut off the top and bottom of the pineapple. Peel, being careful to remove all skin, then cut in half lengthwise.
Using a 1" wide kabob skewer, carefully pierce one half of the pineapple with the pointed end. Move the pineapple half all the way to the other end of the skewer, so it creates a flat base. Layer on a few slices of marinated pork shoulder, then a handful of chorizo, then a layer of white onion rings. Repeat with the remaining pork, chorizo, and onions, being careful to maintain an even, cylindrical shape as you add more layers. Top with the other pineapple half, then rub vegetable oil on the entire assembled skewer and season with salt.
Heat gas grill to medium. Place pointed end of the skewer vertically into the grates, and gently let it lean toward the center of the grill. The skewer should lean at about a 45 degree angle, enough so that the grill lid can still close. Cook with lid open for about an hour, basting with Red Curry Salsa every 15 minutes or so, until edges of the pork facing the grill start to become crispy and caramelized. Flip skewer so the side that was facing away is now turned toward the grill. Close lid and continue to cook for about another hour, until the internal temperature of the pork reaches 150 degrees Fahrenheit. Remove from heat and let rest for 15 minutes.
Use an electric knife to carve thin strips of pork, chorizo, and pineapple from the skewer. Place in lightly grilled corn tortilla, and top with white onion, cilantro, radish slices, and some of the reserved Red Curry Salsa.
Red Curry Salsa
Add vegetable oil to medium sauce pot over medium heat. Add red curry paste, and toast for 3-4 minutes. Then add tomato, onions, garlic, guajillo chilis, and sauté for an additional 3-4 minutes.
Add water and bring to a boil, then reduce heat and simmer for about 10 minutes, until the onions and tomato are soft.
Puree with immersion blender until smooth. Finish with fish sauce and lime juice.
Let cool to room temperature. Reserve half for salsa to top tacos and half to marinate pork.