1 pound fresh mushrooms like shiitake or oyster, shiitakes stemmed and thinly sliced
Kosher salt and freshly ground black pepper
Pinch of dried red chile flakes
2 skinless fillets cod or other firm white fish like snapper or hake (about 1 pound)
1 cup homemade vegetable stock or low-sodium vegetable broth
2 tablespoons cold butter
2 tablespoons fresh squeezed lemon juice from 1 lemon
Fresh cilantro, parsley or chives, for garnish (optional)
Heat 2 tablespoons olive oil in a 12-inch skillet over medium-high heat until barely starting to smoke. Add the mushrooms, season with salt, pepper, and chili flakes, and cook, stirring occasionally, until well browned, 3 to 4 minutes. Transfer to a warmed serving plate and set aside.
Season the fish with salt and pepper. Wipe out skillet, add the remaining olive oil, and return to medium-high heat until shimmering. Add fish fillets and cook without moving until well browned on first side, about 3 minutes. Carefully flip with a flexible metal spatula and cook on second side until just cooked through, about 2 minutes longer. Transfer to plate with mushrooms.
In the same skillet, add 1 cup stock and cook over high heat until reduced by half, about 2 minutes. Off heat, stir in butter and lemon juice. Season to taste with salt and pepper. Pour over fish and mushrooms and serve, garnished with fresh parsley, chives, and/or lemon wedges.
Place the shrimp, imitation crab, celery, red onion, Old Bay seasoning, lemon juice, salt, pepper, mayonnaise and dill in a bowl. Toss gently to coat.
Garnish with additional fresh dill and serve, or cover and refrigerate for up to 2 days.