In a medium sauce pot, combine the black rice and 1¼ cups [2¼ cups] lightly salted water. Bring to a boil, reduce to a simmer, cover, and cook until the rice is tender and the liquid is absorbed, 25 to 30 minutes. Meanwhile, prepare the rest of the meal.

• Trim the root ends from the leek; cut the leek in half lengthwise, then crosswise into ¼-inch-thick half-moons. Soak the half-moons in a medium bowl of cold water, stirring occasionally to loosen any dirt, and allow the dirt to settle at the bottom. Skim the leek from the surface of the water and pat dry.  

In a large frying pan over medium-high heat, warm 1 to 2 tablespoons oil until hot but not smoking. Add the leek, season with salt and pepper, and cook, stirring occasionally, until softened and starting to brown, 4 to 5 minutes. Transfer to a plate. Do not clean the pan. 

While the leek is cooking, prepare the salad.

• Thinly slice the sugar snap peas on the diagonal.
• Zest and juice the lemon, keeping the zest and juice separate. 
• Finely chop the tarragon. Set aside half for the seafood.

In a medium bowl, toss together the snap peas, lemon zest, 1 tablespoon [2 TBL] lemon juice, 1 to 2 teaspoons oil, and half the tarragon. Season to taste with salt, pepper, and more lemon juice, if desired.

Jumbo shrimp: 

• Rinse and drain the shrimp. Pat dry on a paper-towel-lined plate. Season lightly with salt and pepper.

In the same pan used for the leek, warm 2 to 3 teaspoons oil over medium-high heat until hot but not smoking. Add the shrimp and cook, turning once, until firm and cooked through, 2 to 3 minutes per side. Remove from the heat, add the remaining tarragon and as much Marash chile as you like, and toss to combine. Season to taste with salt and pepper. 

Scallops:

• Rinse and drain the scallops. Pat dry on a paper-towel-lined plate. Season lightly with salt.

In the same pan used for the leek, warm 2 to 3 teaspoons oil over high heat until hot but not smoking. Add the scallops and cook without turning until golden brown on one side and starting to turn opaque, 2 to 4 minutes. Turn and continue cooking for about 30 seconds for translucent or 1 to 2 minutes for opaque. Remove from the heat, add the remaining tarragon and as much Marash chile as you like, and toss to combine. Season to taste with salt and pepper. 

Halibut and salmon:

• Pat the fish dry with a paper towel; season lightly with salt and pepper. 

In the same pan used for the leek, warm 2 to 3 teaspoons oil over medium-high heat until hot but not smoking. Add the fish and cook until lightly browned on the bottom side, 4 to 5 minutes. Turn and cook until the flesh is opaque and flaky, 2 to 4 minutes. Remove from the heat and sprinkle with the remaining tarragon and as much Marash chile as you like. 

To the pot with the rice, off the heat, stir in the leek, Parmesan, butter, and 2 tablespoons [¼ cup] warm water. Season to taste with salt, pepper, and any remaining lemon juice.

Transfer the rice to individual plates, top with the seafood, and serve with the tarragon–snap pea salad on the side.