Add the lemon juice to the mango puree and stir well.

Pour this into a thick bottomed sauce pan.

Whisk the corn starch and water in a glass thoroughly. It should be completely free of lumps.

Add this to the saucepan and stir.

Heat this mixture on a low flame.

Constantly stir the mixture to prevent lumps from forming.

The curd will start getting thicker and creamy.

If you have a candy thermometer, it should read 166-170 degrees Fahrenheit.

Test the curd and check if it is sweet enough. If not, add sugar up to a teaspoon at a time. Stir and taste again before adding more.

Turn the heat to simmer and add butter one tbsp at a time.

Stir the curd gently till all the butter has melted.

Take the sauce pan off heat and pour the curd in to a glass jar or a bowl.

Place cling film directly on the surface to prevent skin from forming.

Refrigerate for at least 1 hour or till set.

Use it within 5 days.