This dish is as tasty as it is beautiful. Pink-fleshed Arctic char is closely related to both salmon and lake trout, with a flavor somewhere between the two. If you can’t find any Arctic char, substitute either trout or salmon. Gremolata sounds impressive, but it is just a simple Italian condiment of chopped parsley, garlic and lemon zest. Our version has some chopped pistachios, too, for an extra salty, crunchy bite. It brings a little zing to a straightforward meal of roasted fish and bright asparagus with sweet red onion and concentrated pops of cherry tomato.

1 bunch asparagus (roughly 1 pound total)
1/4 cup extra virgin olive oil
Kosher salt and freshly ground black pepper
4 skinless fillets Arctic char, salmon or trout (5 to 6 ounces each)
1/2 medium red onion, sliced into 1/4-inch-thick half-moons
1/2 lemon, sliced into 1/4-inch-thick rounds
1/2 cup cherry or grape tomatoes
Grated zest of 1 lemon
1 clove garlic, minced
1/2 cup packed fresh flat-leaf parsley leaves, roughly chopped
1/2 cup roasted, salted, and shelled pistachios, roughly chopped

Heat the oven to 350 with a rack in the center position. Mist a sheet pan with cooking spray or line it with parchment paper. Gently bend one asparagus spear between your fingers and snap off the bottom where it breaks easily. Line up the rest of the bunch and slice off the bottoms at the same distance from the tips. Place the trimmed asparagus on the prepared pan, drizzle with the olive oil, and sprinkle with 1/2 teaspoon each of the salt and pepper. Toss to coat, and spread the asparagus in an even layer. Place the fish fillets on top of the asparagus, evenly spaced apart, and sprinkle with an extra pinch of salt and pepper. Scatter the onion, lemon slices and cherry tomatoes around and on top of the fish. Bake until the asparagus is crisp-tender and the fish is almost opaque (20 to 30 minutes if using char, other types may vary). While the fish cooks, mix together the lemon zest, garlic, parsley and pistachios in a small bowl — this is your gremolata. Sprinkle the gremolata over the char and asparagus before serving warm.