Preheat the oven to 425 degrees F. Toss the shrimp with 2 tablespoons of the oil, the cumin, 1 teaspoon salt and 1/2 teaspoon pepper on a rimmed baking sheet. Roast, tossing once, until opaque throughout, 4 to 6 minutes.
Meanwhile, pulse the peppers, cilantro, the remaining 2 tablespoons of oil, lime juice, 1/2 teaspoon salt and 1/2 teaspoon pepper in a food processor until smooth.
Serve the shrimp hot, cold or at room temperature with the sauce. (The sauce can be made ahead and refrigerated for up to 3 days.)
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