Thaw shrimp, if frozen. Peel and devein shrimp, leaving tails intact if desired. Rinse shrimp; pat dry with paper towels. In a large saucepan, bring 4 cups water to boiling. Add shrimp; reduce heat. Simmer, uncovered, for 1 to 3 minutes or until shrimp are opaque. Drain in colander. Rinse with cold water; drain again. Transfer shrimp to a bowl. Add orange peel and the 2 tablespoons orange juice; toss gently to coat.
In a covered medium saucepan, cook asparagus in a small amount of boiling water for 4 to 6 minutes or until crisp-tender. Drain in colander. Rinse with cold water; drain again.
Peel oranges. Working over a bowl, cut oranges into sections; reserve 1/3 cup of the juice. (If necessary, add additional orange juice to make 1/3 cup.) In a small bowl, whisk together the 1/3 cup orange juice, the oil, vinegar, garlic, tarragon, salt, and pepper.
In a large bowl, combine shrimp, asparagus, orange sections, greens, and green onions. Pour dressing over all; toss gently to coat.