While you'll be cooking the shrimp shortly, take a few minutes to prep all your vegetables and herbs so assembly moves quickly. Dice the cucumbers into 1/2-inch cubes, finely dice the red pepper, thinly slice the red onion, cube the avocado, and chop the fresh dill. Having everything prepped and ready prevents the avocado from browning while you're still cooking, which is important for presentation and texture.
Bring a pot of water to a rolling boil with the lemon slices, smashed garlic cloves, and 1 1/2 tsp salt. Once boiling, remove from heat and immediately add the shrimp, stirring gently to ensure they're submerged. Let them sit undisturbed for exactly 4 minutes—this gentle carryover cooking keeps them tender and prevents the rubbery texture that comes from active boiling. The lemon and garlic infuse the shrimp with subtle flavor that complements the dressing beautifully.
Drain the shrimp in a colander, discarding the lemon slices and garlic. Spread them on a plate and let cool for 5-10 minutes while you prepare the dressing. In a bowl, whisk together the Greek yogurt, mayonnaise, lemon juice, lemon zest, dried oregano, 1/2 tsp salt, garlic powder, black pepper, honey, and red pepper flakes until smooth and well combined. The cool shrimp and ready dressing mean you can assemble the salad at the perfect moment without any waiting.
Cut the cooled shrimp in half lengthwise and add them to a large bowl. I like to cut the shrimp this way because it creates more surface area for the creamy dressing to coat and makes each bite more balanced with other ingredients. Add the prepped cucumber, red pepper, red onion, avocado, and fresh dill from Step 1, then pour the dressing from Step 3 over everything. Gently fold the salad together until all components are evenly coated and distributed.