If your shrimp and scallops are frozen put them in a bowl with enough water to cover them while you get the veggies ready.Coarsely chop up the leek (or leeks). Rise them off in a strainer under running cold water until you are satisfied that there isn't and dirt left on them. Chop up the garlic and clean and slice up the zucchini. Cut the lemon into quarters.
Put 2 skillets on the stove with just enough olive oil to cover the bottoms. Add a tablespoon of butter to each one. Add the veggies to one skillet and the shrimp and scallops to the other. But you already figured out that part didn't you. Then salt, pepper and squeeze a lemon wedge into each one.If you want to get adventurous and add a splash or two or three of white wine at this point I'm with you on that.
Stir or toss them as they cook. When the shrimp are pink on both sides and opaque in the middle and the scallops are firm to a poke. And the veggies have softened up. Serve up and enjoy your Leeks with Shrimp or Scallops.