In an 8- to 10-inch frying pan over medium-high heat, stir five spice until fragrant, about 30 seconds. Stir in oil, shallots, and garlic. Add ground pork and stir often, breaking apart with spoon, until meat is crumbly and no longer pink, about 15 minutes. Add soy sauce, sugar, and salt to taste.
Cut baguettes in half crosswise, then split lengthwise almost all the way through, leaving halves attached at one side. Spread about 1 teaspoon chili paste on one cut side of each baguette section. Spoon about 1/6 of the warm ground pork mixture, including juices, over chili paste. Tuck 1/6 of the pork slices evenly into each sandwich. Set sandwiches slightly apart on a 12- by 15-inch baking sheet.
Bake in a 375° regular or convection oven just until filling is warm and crust is crisp, about 5 minutes. Remove sandwiches from oven and fill each with 1/6 of the cucumbers, salad mix, basil, and Fried Shallots. Add more chili paste and salt to taste.