For this delectable seafood dinner, Martha puts fresh swordfish steaks in a citrusy, herby marinade before cooking them under the broiler. For an extra lovely presentation, use cherry tomatoes on the vine.
Preheat oven to 425°F, with a rack 6 inches from heating element. Stir together herbs, 1/4 cup oil, and lemon zest and juice; season with salt and pepper.
Toss tomatoes with remaining 2 tablespoons oil; season with salt and pepper. Arrange tomatoes in a shallow nonreactive baking dish and roast, stirring once halfway through and breaking up some with back of spoon, until burst and beginning to collapse, 15 to 20 minutes. Stir in garlic and red-pepper flakes; roast 5 minutes more. Remove from oven and cover; switch oven to broil.
Meanwhile, season swordfish with salt and pepper and rub half of herb oil over both sides. Let stand 15 minutes. Arrange fish on a broiler-safe pan and broil, flipping halfway through, until cooked through and browned in places, 6 to 8 minutes total. Transfer to dish with tomatoes, slice, and serve, drizzled with remaining herb oil.
When buying seafood, ask to smell it (don't be shy!) to make sure it is fresh. It should smell faintly briny but never fishy.