A few weeks ago, my friend Lisa called me wanting an idea for a simple meal to cook for her boyfriend, Clark. The last time she had cooked for Clark, she proudly called me to report: “I made salad,” she said, “and I even cut the cherry tomatoes.”

“Good Lis,” I said, and we both laughed.

While I thought she might dismiss the idea of soft shell crabs, she believed me when I promised her how easy these crustaceans are to prepare. We decided on a simple side — a baby arugula and shaved parmesan salad — and some fresh bread. Lisa left for the store and called me with an update as she left the fish market. After the fishmonger handed Lisa her cleaned crabs, she had asked, “these will still be dead when I get home, right?” He assured her they would be.

The next I heard from Lisa was much later that evening, a happy text message exclaiming the success of her delectable dinner.

Truly, soft shell crabs take no time to prepare and make a wonderful summer meal. While the aioli nicely complements the crab, a simple squeeze of lemon suffices. Watch Mark Bittman prepare the crabs in this video.

Soft shell crab season, running from early May through August, happens fleetingly. Soft shells are not a separate species of crab, but ones, typically blue crabs, that have molted their shells in order to grow. Because these blue crustaceans grow rapidly, commercial crabbers place the peelers (crabs in the process of shedding) in holding tanks, where they closely monitor the molting process. The crabbers remove the peelers from the water immediately after the crabs shed, to prevent the new, paper-thin shells from hardening, rendering them undesirable.

When buying soft shells, look for a market selling live ones. At Wan’s Seafood in Reading Terminal Market, where active crustaceans lay supine on the countertop, the fishmongers will happily clean the crabs and pack them on ice.

Soft Shell Crab Sandwiches
Serves 4

1 cup low-fat buttermilk
1 egg
½ cup flour
½ cup cornmeal
½ teaspoon kosher salt
freshly ground black pepper to taste
¼ cup neutral oil, canola or grapeseed
4 soft shell crabs, cleaned
8 slices white bread
1 beef steak tomato, sliced
I bunch watercress
Lemon-Caper Aioli (see below)

Whisk buttermilk and egg together and place in a wide-mouth shallow bowl. Whisk flour, cornmeal, salt and pepper together and place on a large plate.

Place oil in a large nonstick skillet over medium-high heat. Meanwhile prepare crabs: dip one crab into buttermilk mixture, then lightly dredge in cornmeal mixture on both sides and place on a clean plate. Repeat with all.

Drop a pinch of flour into oil. If it sizzles, the oil is ready. Carefully place the crabs in the pan and leave undisturbed for 1 minute. Gently shake pan and let crabs cook for 2 to 3 minutes longer or until bottom is nicely browned. Flip crabs and cook for 3 minutes more, or again until browned.

Meanwhile toast the bread. Spread the lemon-caper aioli on four of the slices, top with a handful of watercress and a tomato slice. Top each with a soft shell crab, and finally the top slice of bread. Serve with more aioli or lemon on the side.

Lemon-Caper Aioli
Yield = 1½ cups

2 egg yolks
2 T. Dijon mustard
2 cloves garlic
2 T. fresh lemon juice
1 tsp. kosher salt
1 cup grapeseed oil
3 T. capers
1 bunch basil, finely chopped

Combine yolks, mustard, garlic, lemon juice and salt in a blender or food processor. With motor running, slowly drizzle in the grapeseed oil — drop by drop at first, then more quickly once you see the mixture begin to emulsify. Transfer to bowl, fold in capers and basil. Taste, adjust seasoning with more salt if necessary, and chill until ready to use. Will keep for 2 weeks in the refrigerator.