For chutney, heat 2 tablespoons oil in medium saucepan over medium heat. Cook onions 2 minutes. Stir in remaining chutney ingredients, except ginger, and bring to a boil over medium-high heat.
Reduce heat and simmer, uncovered, 5 minutes or until thickened, stirring frequently. Remove from heat, cool and stir in ginger.
For couscous cakes, bring water to a boil in a small saucepan over high heat. Remove from heat, stir in couscous and salt, cover and let stand 5 minutes. Fluff with a fork and let stand 5 minutes to cool.
Combine couscous, cilantro, egg whites, flour and lemon zest in a medium bowl. Heat 2 tablespoons oil over medium heat. Working with half of the couscous mixture, spoon about 2 tablespoons into skillet to make a mound, repeat, making 8 mounds total.
Flatten slightly using the back of a spoon and cook for 3 minutes each side or until golden. Drain on paper towels. Repeat with remaining oil and couscous mixture.
Serve the couscous cakes with mango chutney.