To make the chili garlic aioli to spread on the sandwiches, combine all the ingredients in a bowl or jar until well combined. Ensure when you use the chiu chow chili oil you get more of the thick chili mixture and less of the oil that sits on top. Refrigerate until ready to use.
Combine the cheese shreds together in another bowl.
In another bowl combine the seasoned jackfruit with kimchi and cilantro, if using.
Heat a large non-stick or cast iron pan over medium-low heat.
Butter one side of each slice of bread. On the other side of each slice spread the chili garlic aioli.
I prefer to assemble the sandwich in the pan to prevent too much spillage transferring it from the cutting board into the pan. Lay 1 slice of bread, butter side down, in the pan. Add the cheese shreds so it covers the entire surface. Top with half the jackfruit mixture. Sprinkle more cheese shreds on top, but less than the first portion you put down. Top with half the arugula and then the other slice of bread butter side up. Place a lid over the pan and reduce heat to low. You'll cook it on the first side for about 6 minutes. But watch it closely as you don't want it to burn. The key is to have the heat low so that it cooks slowly, melting the cheese and warming the entire middle of the sandwich but not cooking the outside of the bread too quickly.
Gently flip the sandwich using a large flat spatula, cover with the lid, and cook the other side for about 4 to 5 minutes or until nice and golden brown. Remove the sandwich to a cutting board and let is rest about 5 to 10 minutes before slicing in half. Assemble and cook the other sandwich.