Make the chicken strips: Cut chicken into strips about 1 inch wide and 3 to 4 inches long.
In a small bowl, combine salt, ground ginger, cinnamon, and cumin. Sprinkle and rub mixture onto chicken strips. Dip strips in beaten eggs, roll in breadcrumbs, and shake off.
In a large skillet, heat oil over high heat. In batches, cook chicken until golden brown, about 1 minute on each side. Drain on paper towels. Arrange strips on serving platter and garnish with lime or lemon slices.
Make the mango sauce. Blend mango puree and 1 cup cold water and process until smooth. Strain and discard fibrous residue.
In a small bowl, stir 1/4 cup cold water into cornstarch. Pour strained mango mixture into a large saucepan and set over medium-high heat. Stir in lime or lemon zest, lime or lemon juice, ginger slices, marmalade, and sugar. Cook, uncover, 10 minutes, stir. Reduce heat to medium and stir in cornstarch mixture. Simmer until thick, 12 to 15 minutes. (Remove ginger slices, if desired.)