The key to this dish is to leave the heavy lifting to a fish purveyor, who often will steam the shellfish and shuck the oysters for a minimal charge. Make the simple sauces earlier in the day, and your work is done. For the serving tray, buy crushed ice or place a few cups of ice in a plastic bag, wrap in a dish towel, and crush using a rolling pin or a meat tenderizer.
Baby spinach and red mustard leaves are more tender and spicy than the familiar varieties of those greens. You can use other spicy baby lettuces, such as chard and tatsoi, or look for packaged blends (sometimes called spring or Asian mix) in many supermarkets.
This all-purpose tomato-based sauce balances sweet and savory. Use this recipe on its own or as a base for the easy-to-make variations: Smoky Chile and Coffee, Roasted Garlic and Lemon, or Peach and Bourbon.