Bring a large pot of salted water to a boil over high heat. Add garlic cloves, lemon halves, and chile. Add in shrimp and simmer until pink, about 5 minutes. Remove and rinse under cold water.
In a large bowl, toss shrimp, scallions, red onion, capers, celery, and tomatoes together.
In a small bowl, whisk together oregano, olive oil, salt, pepper, lemon juice, and vinegar. Pour over the salad and toss once more to incorporate. Cover and refrigerate until ready to serve.
Recipe courtesy of Cat Cora