Bring 1 1/2 cups water to a boil in a saucepan over high heat. Remove from heat, and stir in couscous; let stand 10 minutes. Transfer couscous to a large bowl.
Stir together olive oil, lemon rind, and next 3 ingredients; add to couscous, stirring with a fork.
Toss peas, sliced onion, crumbled feta, and chopped mint gently into couscous; cover and chill at least 2 hours. Stir in pine nuts just before serving.
Prep: 30 min., Chill: 2 hrs.