Would it be OK to halve the recipe for Strawberry Ice-Cream if I don't want to make a large batch? Also, would it be fine to use strawberries bought fresh during the season but frozen in the freezer?
Nigella's Strawberry Ice Cream (from NIGELLA SUMMER) is a custard-based ice cream that is mixed with a strawberry puree. It is fine to make a half quantity of the recipe if you don't want to make a full batch and the ingredient quantities are easy to halve.
As a general rule you should not thaw foods and re-freeze them as there is a risk of bacteria growing during the thawing periods. This is particularly for protein-based foods. Strawberries don't contain significant amounts of protein, but there is still always a little risk and so it is not something we would recommend. If you want to use frozen and thawed strawberries then we suggest that you thaw them overnight in the fridge then put them in a saucepan over a medium heat and bring them up to boiling point. Take the pan off the heat and stir in the sugar, then let the mixture cool and chill it before using. The thawed strawberries will be mushy when they defrost, so there is less reason to let them macrate with sugar in step 1 of the recipe. Frozen strawberries can also lose some of their flavour, so you may also like to add a squeeze of lemon juice to the cooled puree. Taste the puree first and then add a few drops of juice at a time to brighten the flavour, if necessary.