750ml whole milk
30g Lapsang Souchong tea leaves
2 tbsp liquid glucose
60g fresh mint leaves (about 45g de-stalked)
100g vanilla sugar
2 tbsp flour
200ml single cream
397g can condensed milk
Step 1) Bring 500ml of the milk to boiling point in a medium saucepan, add the tea leaves and stir vigorously. Turn off the heat, cover and leave to stand for 10 minutes.
Step 2) Strain through a sieve over a measuring jug, pressing the leaves to extract their flavour. Repeat for a second straining, then discard the leaves. Stir in the glucose and cool over ice. Pour 300ml of the tea liquid into a food processor, add the mint and blitz until well chopped. Return this liquid to the jug.
Step 3) To make the custard base, whisk together the vanilla sugar, eggs and flour in a large heatproof jug. Bring the remaining milk and all the cream to the boil in a medium saucepan, then pour this onto the egg mixture and whisk for 30 seconds. Return the custard mix to the pan and cook over a medium heat, whisking constantly for 11⁄2-2 minutes or until it thickens. Remove the pan from the heat and stir in the condensed milk.
Step 4) Cool the pan in iced water. Whisk in the tea liquid and chill. Pour into a chilled ice-cream maker and churn until firm (20-25 minutes); or fast-freeze in a 1-litre freezer container for 3 hours, remove and whisk briefly, then freeze for a further 2 hours. Soften for 10 minutes before serving.