In this simple recipe, orange sweet potatoes and bright green kale sauté in one skillet, while fish coated with whole grain mustard cooks in another. I purchase pink-fleshed, delicately flavored char whenever I find it.
Olive oil, 3tablespoons, plus more as needed
Red onion, ½ large, sliced
Red pepper flakes, ¼teaspoon
Orange-fleshed sweet potato, 1 (about 10oz/315g) peeled, quartered lengthwise, and then cut crosswise into ¼-inch (6-mm) thick slices
Kale, 1bunch, rinsed, stemmed, leaves thinly sliced crosswise, with the water still clinging to them
Kosher salt and freshly ground black pepper
Fresh lemon juice, 2tablespoons
Arctic char or wild salmon fillets, 4 (about 6oz/185g) each)
Gluten-free whole-grain Dijon mustard, about 4teaspoons
Kalamata olives, ¼cup (1½oz/40g) pitted, cut lengthwise into quarters (optional)
In a 12-inch (30-cm) nonstick frying pan over medium-high heat, warm 2 tablespoons of the oil. Add the onion and pepper flakes and sauté for 3 minutes to soften slightly. Add the sweet potato and stir for 1 minute to coat with the oil. Add the kale and stir to coat. Sprinkle lightly with salt and black pepper, and the lemon juice. Cover, reduce the heat to low, and cook, stirring occasionally, until the sweet potatoes are just tender and the kale wilts, about 12 minutes.
Meanwhile, brush the flesh of the fish with olive oil, and season with salt and black pepper. Spread the mustard over the top of each fillet. In another large nonstick frying pan over medium-high heat, warm the remaining 1 tablespoon oil. Add the fish skin side down. Cover and cook, without turning, until the fish is just springy to the touch and opaque in the center, about 6 minutes.
If using the olives, stir them into the vegetables, and then season them to taste. Divide the vegetables among 4 warmed plates. Place one fish fillet alongside the vegetables on each plate and serve right away.