I remember being at school with a lad who's dad owned the Indian in town, I had asked him several times how they made stuff but he said he was only making the dip's, so this is the mint sauce that they made From about 25 years ago
1 cup natural yogurt
1 tsp. mint sauce
1 tbsp. mango chutney
2 tsp. lime pickle
1-2 tsp. sugar to taste
blend until smooth, may be thinned with a bit of milk.
Fairly simple, you may have to adjust chutney and pickle to taste, should be sweet with a spicy sour after taste. Haven't made this for ages and I don't remember using food colouring.