Trim any excess fat and sinewy pieces from the outside of the pork loin.
Mix together the thyme, allspice, cinnamon, lime juice and honey and rub all over the outside of the pork.
Remove the outer leaves form the romaine (keep to use another time) and cut in half top to bottom through the stem. Remove the core and seeds from the pepper and cut into quarters. Snap the ends of the asparagus stalks. Lightly drizzle all with a little oil (only a small amount) and rub all over. Trim the skin from the pineapple.
Grill the pork, romaine, pepper, asparagus and pineapple, turning each as required. The pork will talk around 20min to be cooked through, the rest will take a little less - you just want them all lightly browned. Watch the romaine as it will quickly go from uncooked to charred black if you are not careful.
While everything is cooking, whisk together the orange juice, lime juice, oil and mustard for the dressing, plus the chili if using.
Once everything is cooked on the grill, remove from the heat and chop each into bite-sized pieces (the pineapple into around 8 pieces a slice, asparagus in half or thirds per stem, pepper in 4 to 6 pieces per quarter, pork and romaine sliced). Cut the pork last so it has time to rest a little.
Layer up the salad with the romaine at the bottom, the vegetables and pineapple next then pork on top. Drizzle over the dressing. Can be eater warm straight after cooking or allowed to cool to room temperature. If eating cooler, it's probably best to wait until nearer when serving to pour over the dressing.