If you've purchased frozen seafood, thaw it in a container lined with several layers of paper twoels. Replace towels as they become saturated. For the best color and sear, you want to have the driest scallops or shrimp possible. If your jumbo shrimp are in the shell, remove it before cooking.
Prepare the Tomatillo and Avocado salsa. Combine all ingredients in the bowl of a food procesor or blender. Pulse until it forms a sauce, ensuring it still holds some texture. Set aside.
Prepare the Corn and Tomato salsa. Remove the husks and silks from the corn. Cut kernals from each cob, catching them in a medium bowl. Remove any stray corn silks. Add the tomatoes, cilantro, white vinegar, and cumin. Mix well. Season with salt and pepper to taste. Set aside.
When ready to cook, pat the seafood dry with a paper towel, then season well with salt, pepper, and a dusting of ground cumin.
If using scallops, heat a heavy non-stick pan under high heat. Add one tablespoon olive oil and heat until it shimmers. Carefully place the scallops in the pan. Do not crowd, or you will not get a good sear. Gently press each scallop against the pan with your fingers or a spatula. Sear the scallops, undistrubed, until they've turned white halfway up the side, then carefully flip them and cook one to two additional minutes. Be careful not to overcook, or they will be rubbery. Remove from the pan to a paper towel lined plate to drain.
If using shrimp, heat a heavy non-stick pan over high heat. Add one tablespoon olive oil and heat until it shimmers. Carefully place the shrimp in the pan. Do not overcrowd or hyouwill not get a good sear. Allow the shrimp to sear until they have curlked and are pink half way through. Flip and cook for an additional one to two minutes. Be careful not to overcook or they will become rubbery. Remove to a paper towel-lined plate to drain.
To serve, Place the scallops or shrimp on the plate. Spoon the tomatillo avocado salsa over each piece, then arrange the corn and tomato salsa around it.