In a food processor, combine all ingredients and process until smooth. Season with salt and pepper. In a bowl, gently combine the crab, red pepper, and celery. Add spoonfuls of the avocado mayo to adjust the moistness to your liking. For my two rolls, I used approximately 3 tablespoons of the avo mayo. Fold in the avocado gently. Taste for seasoning. Assembly - OPTIONAL to use the buttercrisp lettuce - I like the crunch on mine - my husband and son prefer to leave the "salad" out of their roll. Its up to you. Layer (or not) a few leaves of lettuce in the bun. Heap on the crab salad. Sprinkle with Old Bay and top with chives.