The pork belly in this recipe is braised in a gluten-free beer brine so that even the most wheat-intolerant can enjoy this sophisticated twist on a sandwich classic.
In a small saucepot, combine 1 cup of salted water with the gluten-free beer, garlic, white onion, and the orange peel and bring to a boil. Boil for 15 minutes, remove from heat, and cool. Submerge the pork beller into the brine, cover, and refrigerate for 36 hours.
Remove the pork belly from the bring and place in a saucepot with the vegetable stock. Cook on low heat or in the oven until tender, about 4 hours. Remove from heat and let cool. Once fully chilled, place the pork belly skin side down in a hot skillet with the olive oil, turn heat to low, and place a weight or bacon press on top of the pork belly to ensure even browning and crisping. Remove from the heat and slice into ¼-inch thick pieces for the sandwich assembly.
In a small sauté pan, cook the arugula and add to a food processor or blender with the mayo, lemon juice, and salt. Purée until smooth.
Assemble the sandwich by lathering the arugula-mayo on each slice of bread and place 1 slice of tomato and the slices of pork belly on top.