You can add chutney, curry, chopped cucumber or chopped egg to this.
2 eggs, beaten
1 teaspoon salt
1 teaspoon mustard
1 14-ounce can sweetened condensed milk
1 cup vinegar
Beat the eggs, salt, mustard and milk vigorously for a few minutes. Add the vinegar, stir well and set aside for 3 or 4 hours to thicken.