For the sandwich: Preheat the oven to 350 degrees F. Have the pork at room temperature. Season it with salt and pepper. Put the roast into a baking pan and roast until the internal temperature reaches 150 degrees F, 40 to 45 minutes. Cover the pork with foil and let it rest for 15 minutes. If not using right away, the roast can be wrapped and refrigerated for up to 2 days. When you are ready to make the sandwich, thinly slice about three-quarters of the pork roast (reserve the remaining one-quarter for Round 2 Recipe Black Bean and Pork Stew).
Heat a grill pan over medium heat. Spread a thin layer of mustard on both sides of the bread pieces. Place 2 slices ham on the bottom half of each. Top with the sliced pork roast, then the pickles, and then the Swiss cheese. Place the top half of the baguette on top. Brush the grill with canola oil and place the sandwiches, cheese side down, onto the grill. Set a baking sheet on top of the sandwich and weigh it down with a heavy skillet or pot. Cook until the bottom is crisp and the cheese is starting to melt, 4 to 5 minutes. Flip the sandwich over, replace the baking sheet and weight, and cook another 3 to 4 minutes.
For the plantain chips: In a 2-inch deep cast iron skillet, heat the oil to 350 degrees F.
Peel the plantains by slicing off about 1-inch from the top and bottom of each. With a paring knife, make a slice on each side the length of the plantain, making sure to go just deep enough to cut through the skin but not cut into the flesh. Peel the skin off to expose the flesh. If you have trouble peeling the skin then cut it off in strips with the knife. Cut each plantain in half and, using the slicing side of a box grater, slice the halves into thin chips.
Cook the plantain slices in batches until they crispy, 3 to 4 minutes. Drain on brown paper or paper towels and season with salt.