1. In a mixing bowl, whisk the lemon juice and olive oil together. Season with salt and pepper. (This can be done ahead and kept in the refrigerator for 1 day.)
2. Add the chives.
For the salad:
1. Rinse the couscous in a sieve under cold water until the water runs clear. Add the couscous to 3 cups boiling salted water. Simmer over medium heat, stirring occasionally, until al dente, about 12 to 15 minutes. (Check the package directions for more exact cooking times.) Cover, remove from the heat and let stand 10 minutes. All the liquid should now be absorbed. Return the couscous to the sieve and rinse under cold water for about 3 minutes, until cool. Drain and place in a large bowl.
2. Toss the couscous with 1 tablespoon olive oil.
3. Toss the onion with the remaining tablespoon olive oil and the balsamic vinegar and season heavily with pepper. Spread the onion slices evenly on a baking sheet and roast at 375° F until softened and caramel-colored, about 15 to 20 minutes.
4. Toss the couscous with the onion, red pepper, cherry tomatoes, artichokes, cucumber, scallions, turkey and lemon-chive vinaigrette. Season with salt and pepper, and chill in the refrigerator until ready to serve. If the salad is too dry, spritz it with lemon juice and olive oil.