1. Heat oven to 350°F  (if the bread is GF or you choose to toast it).  

Make the Pistachio Pesto.  

1. In the food processor, pulse a cup of raw pistachios until coarsely chopped. Add the pressed garlic, basil, and parsley. When all of that is mixed well, slowly add a half cup of olive oil until combined well. Add the lemon juice, salt, and pepper and combine until well mixed. Depending on your desired consistency, add more olive oil, 2 tablespoons at a time (I usually end up adding 4 tablespoons), and set aside.  

Make the Peppadew Pepper Mayo. 

1. In a food processor, combine the mayonnaise, jarred peppadew peppers, and brine. Pulse until completely combined. Set aside. 

Make the sandwich.  

1. Slice your bread lengthwise and scoop out the inner bread from the middle. If using gluten-free bread, you will want to toast it but if using regular bread, toasting will be optional, and you can skip the toasting step if you prefer it softer.   
2. If toasting your bread, brush the cut sides of the bread with olive oil and place on a parchment-lined sheet tray, cut side up. Put in the oven for a few minutes until lightly toasted, or toasted to your preference. Remove the sheet tray from the oven and place the bread on a cutting board.  
3. Spread a few tablespoons of the pistachio pesto on one of the bread halves and a few tablespoons of the peppadew pepper mayo on the other.  
4. Add a few slices of mortadella on the peppadew pepper mayo, drizzling it in gentle ribbons. Add a handful of arugula on top of the pistachio pesto and salt your greens.  
5. Tear a ball of burrata open and top the mortadella as evenly as you can and sprinkle it with ground pepper.  
6. Add marinated onion on top of the arugula.  
7. Swiftly close the sandwich by placing the pistachio pesto side over the other. 
8. Cut the sandwich in two. Serve cold and enjoy!