Combine orange juice, oil, vinegar, shallot, salt and pepper in a blender. Puree until smooth.
Toss lettuce, blueberries, onion and tarragon with half the vinaigrette in a large bowl. Divide among 6 dinner plates. Gently mix lobster (or crab) and the remaining vinaigrette in the bowl. Divide among the salads and sprinkle with almonds.
224 calories;13 g fat(2 g sat); 2 g fiber; 10 g carbohydrates; 17 g protein; 35 mcg folate; 110 mg cholesterol; 5 g sugars; 2 g added sugars; 3,566 IU vitamin A; 11 mg vitamin C; 111 mg calcium; 1 mg iron; 574 mg sodium; 376 mg potassium