Hull and roughly chop the strawberries, put them into a bowl and sprinkle over the 2 tablespoons of caster sugar and leave them to steep and infuse with flavour.
Pour the milk and cream into a heavy-based saucepan, and add the vanilla pod, split down the middle lengthways. Bring the pan nearly to the boil and then take it off the heat and leave to infuse for 20 minutes.
In a large bowl whisk the egg yolks and the 175g / ¾ cup sugar until thick and pale yellow. Take the vanilla pod out of the milk and cream and pour, whisking the while, the warm liquid over the yolks. Put the cleaned-out pan back on the heat with the cream, milk, egg and sugar mixture and stir the custard until it thickens, then take it off the heat and pour it into a bowl to cool.
Puree the strawberries in a processor, and when the custard is cool fold in the lemon juice and strawberry puree.
At this point you can either freeze the ice cream in an ice-cream maker, or in a plastic tub in the freezer. If you do the latter you should whip it out every hour for 3 hours as it freezes and give it a good beating, either with an electric whisk, by hand or in the processer. That gets rid of any ice crystals that form and that make the ice cream crunchy rather than smooth.