Place shrimp and blackened seasoning mix in a re-sealable plastic bag (you may need to divide shrimp into two batches). Shake contents of bag to distribute seasoning evenly.
Heat two teaspoons of olive oil in large-skillet, and add half of the shrimp in a single layer. Cook about 2 to 3 minutes per side, until shrimp are pink and cooked through. Repeat with remaining olive oil and shrimp.
For the avocado crema: Combine Greek yogurt, avocado, and one tablespoon of lime juice in blender or food processor. Blend until smooth.
For the tomato salsa: Stir the tomatoes, green bell pepper, onion, cilantro, jalapeño pepper, and remaining tablespoon of lime juice in a medium bowl.
Prepare lettuce wraps by dividing the shrimp, avocado crema, and tomato salsa evenly among the lettuce leaves. Serve immediately.