Prep the shrimp. If they're frozen, run them under cool water until thawed. Peel them if they're not already peeled, but leave the tails on. Pat them dry and add them to a bowl along with the seafood marinade. Let them marinate for 15 minutes.
Meanwhile, cook the orzo al dente according to package directions. Once it's done, rinse it with cool water (let it drain thoroughly). Add it to a large salad bowl once cool.
Preheat your BBQ/grill/grill pan to high heat. I used a gas BBQ with the lid closed, but timing will depend on your specific grill.
For the corn: remove the husks and silks and coat the corn with olive or vegetable oil. Cook for 10-12 minutes, rotating every few minutes until it's cooked though and you see char marks.
For the shrimp: thread shrimp onto skewers (if using wooden skewers, be sure to soak them first), then grill them over medium-high heat (turn the heat down after doing the corn) for 2-3 minutes/side. I like mine a little extra charred, so I grilled them for 3 minutes/side, but be sure not to overcook them or they will turn rubbery.
Prep the remaining ingredients (chop the spinach and scallions and zest the lemon) and add them to the salad bowl while the corn and shrimp cool for a few minutes.
Cut the corn off the cobs and add it to the salad bowl. Toss with the dressing. You can either remove the shrimp from the skewers and serve them on top of the salad or place a skewer on top of each bowl/plate once served.