Heat 2 teaspoons oil in a dutch oven or deep skillet over medium-high heat. Add onion and carrots. Cook for 3-5 minutes.
Add garlic, curry powder, turmeric, and ginger and cook, stirring, for 30 seconds or so.
Add the remaining 1 teaspoon of oil. Add chicken breast and cook for 5-7 minutes, or until browned.
Add tomatoes and broth. Bring to a boil. Stir in couscous. Remove from heat and let it stand , covered, for 8-10 minutes.
Fluff with a fork and squeeze in lemon and zest. Add cilantro/parsley and any other toppings you wish.