Marinate the shrimp: Pat the shrimp dry with paper towels. In a medium bowl, whisk together the olive oil, lime juice, lime zest, garlic, cumin, smoked paprika, red pepper flakes, salt, pepper, and cilantro. Add the shrimp and toss until evenly coated. Cover and refrigerate for 15 to 30 minutes.
Make the pickled onions: While the shrimp marinates, combine the apple cider vinegar, honey, salt, peppercorns, garlic, and bay leaf in a small saucepan. Heat just until the honey and salt dissolve. Place the sliced onions in a heatproof jar or bowl and pour the warm pickling liquid over the onions. Let stand for at least 20 minutes.
Prepare the dressing: In a small bowl, whisk together the olive oil, lime juice, Dijon mustard, honey, salt, and pepper until smooth and emulsified.
Assemble the salad: In a large serving bowl or platter, combine the mixed greens, cucumber, tomatoes, avocado, and corn. Drizzle with the vinaigrette and toss gently just before serving.
Grill the shrimp: Preheat a grill or grill pan over medium-high heat. Thread the shrimp onto skewers. Grill for 2 to 3 minutes per side, or until opaque and lightly charred.
Finish and serve: Remove the shrimp from the skewers and arrange over the salad. Top with the pickled onions and remaining cilantro. Serve immediately with lime wedges for squeezing over the top.