• 1 lemon
• 3 tablespoons extra-virgin olive oil plus more for greasing pan
• Fine sea salt
• 1 1/2  cups fresh shelled or frozen peas
• 2 whole mackerel (about 1 1/3 pounds each), cleaned, butterflied and cut crosswise into pieces about 2 inches wide
• 1/2  cup finely chopped drained oil- packed sun-dried tomatoes
• 1/3  cup finely chopped flat-leaf parsley

Heat oven to 400º.

Using a vegetable peeler or sharp paring knife, remove zest from lemon in wide strips, avoiding white pith. Set aside zest (save lemon for another use).

In a small saucepan, combine oil, half of the zest strips and pinch salt; gently heat over low heat until oil just begins to bubble; remove from heat and set aside.

Meanwhile, bring a small saucepan of salted water to a boil; add peas and remaining zest strips; cook until peas are just tender, about 2 minutes. Drain peas, remove and discard zest. Add peas to saucepan with oil.

Grease a 9- x 13-inch baking dish with oil. Season fish with salt, then arrange flesh-side up in prepared baking dish. Bake 10 minutes, then sprinkle with tomatoes and parsley and continue baking until fish is opaque and cooked through, about 5 minutes more. When fish is close to done, gently heat oil with peas and generous pinch salt just until oil is bubbling; remove from heat.

Arrange fish on serving plates; spoon peas and oil over the top. Serve warm.