1. In a medium saucepan, combine 2 cups chicken stock, olive oil, saffron, and salt. Bring to a simmer over medium heat for 5 minutes, stirring to dissolve salt. Remove from heat and let stand at room temperature for 30 minutes to infuse saffron flavor.

2. Fill the bottom of a couscoussier half-full with water. Add carrots, onions, celery, and parsley; bring to a simmer.

3. Place the couscous in a very large glass bowl; pour the infused stock over couscous, straining to remove saffron, if desired. Let couscous absorb the liquid, stirring occasionally, about 15 minutes.

4. Scoop up some of the couscous and rub it with your fingers to separate any lumps, letting it fall back into the bowl. Repeat process until no lumps remain.

5. Meanwhile, increase heat under couscoussier to bring water to a gentle boil; add more water if needed to maintain level.

6. Transfer couscous to a steamer basket set over a plate to catch any grains (returning them to the basket if they do). Run fingers lightly over top to make sure couscous is evenly distributed; set steamer basket over gently boiling water in couscoussier. If necessary, carefully wrap a large piece of plastic wrap around the rim of bottom pot to keep steam from escaping. Once couscous begins to steam, steam for 30 minutes.

7. Carefully remove plastic wrap, if using, and then steamer basket, pulling toward you so you do not get burned by escaping steam. Spread couscous on a terra-cotta tray or in a bowl and let stand until cool enough to handle.

8. Meanwhile, add enough water to bottom of the couscoussier to bring its level back to the halfway point. Return to a boil. Clean and dry the steamer basket, discarding any couscous that stuck to it.

9. Repeat process in step 4 to separate couscous. When couscous returns to room temperature, transfer couscous to cleaned steamer basket; add plastic wrap, if needed, and steam until tender and appears sweaty, 15 to 30 minutes. Spread couscous out on tray or in bowl and let cool.

10. Place remaining 1/2 cup chicken stock in a clean spray bottle or small bowl. Return couscous to steamer basket; set over couscoussier; bring to a gentle boil. Immediately begin to add remaining stock, spraying couscous 15 to 20 times or drizzling with about 2 tablespoons over grains. Continue adding stock and stirring occasionally for about 15 minutes. Transfer couscous to tray or bowl. It should have doubled in size to about 6 cups.