- Into a large skillet over medium high heat, add vegan butter. When butter is melted, add hearts of palm. Saute 8-10 minutes, until golden brown. 
- Add red pepper, yellow onion, and garlic; continue cooking 2-3 minutes, until softened. Remove from heat. 
- Into a medium bowl add vegan mayonnaise, lemon juice, cayenne pepper sauce, tarragon, celery, and salt and pepper, to taste. Add hearts of palm mixture and toss gently to coat. 
- If serving chilled, refrigerate for at least one hour. 
- Layer lettuce into toasted buns. Add hearts of palm mixture then top with a sprinkling of scallions and Old Bay seasoning and serve.