Heat oil in a large nonstick skillet over medium heat.
Add shrimp to pan, sauté for 1 minute.
Add mustard to pan; sauté for 2 minutes, stirring frequently.
Stir in onions and cook for 1 minute.
Remove from heat and stir in diced mango.
Sprinkle with cilantro and serve with lemon wedges over rice or orzo.