Make the garlic mayonnaise: Add the minced garlic, the egg yolk, the mustard, and the black pepper to a small bowl. Give everything a little stir, to incorporate.
Slowly incorporate the oil in a very thin stream, while constantly beating with a fork or mini whisk. (Add a little oil at a time, waiting until the oil has 'disappeared', before adding more.) The whole process should take about 5 minutes--the mayonnaise will have risen in the bowl and turned a paler yellow. You should also be able to tip the bowl over without the mayonnaise falling out.
Let the mayonnaise rest in the fridge, covered, for at least one hour before use. (This can also be made a night ahead.)
Put the lobster salad together: Wash and thinly slice the scallions. Add them to a medium-sized bowl.
About the lobster: my fishmonger happens to sell freshly-cooked, whole lobsters. You can also buy live lobsters, and cook them yourself.
Chop your lobster into bite-sized pieces, and then add them to the medium bowl. Also add: the lemon juice, the cayenne, and the mayonnaise. Gently toss all ingredients together, to incorporate. Cover with plastic, and move to the fridge while you assemble the sandwich ingredients.
You have two bun-toasting options: 1) Melt the butter in a non-stick pan. Cut the buns in half, and toast them in the butter. 2) Toast them without butter in a toaster oven. (Obviously, the butter option is more delicious.)
Layer 1-2 leaves of lettuce on each bun. Pile a generous scoop of the lobster salad on top of the lettuce.
Optional: layer some Cape Cod potato chips into the sandwich. (They provide salt and crunch.) You can also simply serve the sandwich with the chips on the side.
Cristina is a writer, cook, and day job real estate developer. She studied literature, holds an MFA in Fiction Writing, and completed the Basic Cuisine course at Le Cordon Bleu in Paris. She lives in Jersey City with her husband--a Frenchman she met in Spain--and their sweet black cat, Minou. Follow her writings, recipes, publications and photography at theroamingkitchen.com.