Combine first 8 ingredients; gradually whisk in 3 tablespoons oil.
Heat remaining 1 tablespoon oil in a large skillet over medium-high heat. Add shrimp; cook 2 minutes. Add juice mixture; cook 1 minute. Stir in asparagus. Place romaine in a large bowl; toss with shrimp mixture. Divide salad among 4 plates; top each with 1/4 cup watercress.
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