In a small bowl, dissolve cornstarch in lime juice.

Dissolve cornstarch and mustard in the vinegar; put on to thicken.

To sauce in pan, add dissolved cornstarch; cook, stirring, over high heat until sauce thickens.

Dissolve cornstarch in remaining half-cup water and add to the curried chicken and stir well.

Stir until it begins to boil, then stir in the dissolved cornstarch until the custard is very thick.