Combine the lemon juice and zest, garlic, olive oil, sugar and parsley in a bowl. Add the shrimp, crab, smoked salmon, yellow pepper, snap peas and cherry tomatoes and gentle toss to combine. Marinate in the fridge 20 minutes. Arrange the salad greens on the bottom of 4 plates. Divide and fan out the pomelo slices on one side of the plate. Gentle toss the seafood mixture again and then mound on the other side of the plate and serve.