Cook the Shrimp. Warm a skillet over medium heat with a tbsp of olive oil and add the shrimp. Cook for 2-3 minutes, or until the shrimp are cooked through. Set aside to cool.
Prepare the Salad Greens. Wash and dry the mixed greens and place them in a large salad bowl.
Chop the Vegetables. Dice the cucumber and bell peppers, and thinly slice the red onion. Add them to the salad bowl with the greens.
Prepare the Dressing. In a small bowl, whisk together the lemon juice, lemon zest, olive oil, minced garlic, salt, and pepper until well combined.
Assemble the Salad. Add the cooked shrimp and diced avocado to the salad bowl with the vegetables. Drizzle the dressing over the salad and toss gently to coat everything evenly.
Serve and Enjoy. Divide the shrimp salad among serving plates or bowls. Garnish with fresh herbs, if desired, and serve immediately.