In a large bowl, combine oil, lime juice, honey, garlic, and Cajun seasoning. Season with salt. Add shrimp and toss until fully coated, then cover and refrigerate for 30 minutes or up to an hour.
In a large skillet over medium heat, cook shrimp until pink and completely opaque, about 2 minutes per side. Remove from heat.
In a medium bowl, mash avocados. Add lime juice, red onion, jalapeno, and cilantro and stir to combine. Season with salt.
Place a tablespoon-sized dollop of guac on each cucumber slice. Top with shrimp and garnish with more cilantro.
Maintaining a firm crunch in fresh produce requires strict limits on moisture exposure, which this dish manages by timing the assembly right before serving. Preparing components ahead is possible if moisture barriers are maintained. Scaling quantities requires keeping the oil-to-acid ratio constant when multiplying the marinade.
Marinade Timing
The acid in the lime juice cures proteins if left too long. Limit the shrimp marinade window to between 30 minutes and one hour. Beyond that threshold, the exterior texture turns mushy rather than firm.
Heat Management
Shrimp cooks rapidly and transitions from translucent to opaque in about two minutes per side over medium heat. Watch for a bright pink exterior and a tightly curled C-shape as visual indicators of doneness. Pull the skillet off the burner immediately to avoid rubbery seafood.
Guacamole Stabilization
Avocado oxidation causes rapid browning. Pressing plastic wrap directly against the surface of the mashed avocado mixture seals out oxygen during storage. Adding extra lime juice slows the enzymatic browning process further if holding the dip longer than an hour.