Cure the shrimp: In a glass bowl, toss shrimp with lime juice and ½ tsp salt. Cover and chill 15–20 min, stirring halfway, until shrimp turn opaque and pink.
Drain (but reserve): Pour the curing liquid through a sieve into a cup; you'll use a splash of this later.
Combine the greens: In the same bowl, add tomatillo, avocado, jalapeño, red onion, and cilantro. Drizzle with olive oil, 2 Tbsp reserved lime juice, and a pinch of pepper.
Fold & season: Gently fold in the cured shrimp. Taste; add more salt, pepper, or lime juice as you like.
Chill or serve: For best flavor, chill 10 minutes so everything mingles. Serve in lettuce cups, small glasses, or over spiralized zucchini.