UNION SQUARE CAFE'S TUNA CLUB SANDWICH

Steps:

• Make aioli: Combine egg yolks, lemon juice, vinegar, mustard, garlic and salt in a food processor.
• With the machine running, slowly add the olive oil in a constant stream through the feed tube until all the oil is absorbed and the mixture has the consistency of mayonnaise.
• Add pepper and mix 10 seconds.
• Transfer to a bowl, cover and refrigerate.
• Combine 4 cups water, onion, carrot, celery, bay leaf and peppercorns in a 2-quart saucepan and bring to a boil over high heat.
• Lower to simmer, cover and cook for 15 minutes.
• Add the tuna pieces and simmer until they are barely cooked through, about 10 minutes.
• Remove the cooked tuna from the cooking liquid to a bowl using a slotted spoon.
• While the fish is still warm, flake it into small pieces with a fork or your fingers.
• (The fish firms up as it cools and will not flake as nicely.) Cover loosely and let cool.
• Crush the fennel seeds between two sheets of waxed paper; dry fry in a small skillet until fragrant.
• Place in large bowl; add 1/2 cup aioli, the red and yellow peppers, onion, herbs and salt and set aside.
• Mix the flaked tuna into the fennel mixture.
• Combine well and taste for seasonings, adding salt, pepper and lemon juice as needed.
• (The tuna salad can be made ahead to this point without the herbs and refrigerated until the next day; stir in the herbs just before using.) Spread a slice of sourdough bread with the aioli, then with a spoonful of the tuna salad.
• Top with a few leaves of the arugula and one slice of bacon.
• Repeat with a second slice of sourdough.
• Stack one layer on top of another and finish by topping with a third slice of sourdough.
• Repeat to make three more club sandwiches.
• Slice each sandwich into halves or thirds and secure each piece with a toothpick.