Bring water to a rapid boil over high heat. Add dry couscous and Kosher salt, then return to a boil. Reduce the temperature to a simmer, then cover the pan and cook.
In a measuring cup, combine extra virgin olive oil, fresh lemon juice, lemon zest, chopped oregano, thinly sliced chives, and thinly sliced shallot. Stir well.
When couscous is fully cooked, pour the dressing on top. Toss very well. Stir in crumbled feta cheese, then taste and adjust seasoning as needed. Garnish with freshly cracked black pepper before serving.