Heat oil in a large nonstick skillet over medium heat.
Add onion, ginger, and pepper; cover and cook 7 minutes, stirring occasionally. Stir in the sugar and next 7 ingredients (sugar through allspice); cover and cook 5 minutes. Increase heat to medium-high.
Add the mango, and cook for 4 minutes or until liquid almost evaporates. Stir in mint.