- In a bowl, combine the tuna, green onion, pesto, mayonnaise, cilantro, and sambal oelek with a fork. Season with pepper.
- Spoon the tuna filling on the English muffin bottoms. Add the arugula and close with the English muffin tops.
- In a ridged skillet or panini grill, brown the sandwiches on each side. Cut in half and serve with a green salad.