Use the oil to lightly grease the inside of a 600ml jelly mould. Put the gelatine leaves in a small bowl of cold water, one at a time so they don’t stick together. Leave to soak while you cook the raspberries.
Pour 300ml water into a large saucepan. Add the caster sugar, heat gently over a medium heat, stirring occasionally until the sugar has dissolved, then add the raspberries. Bring to the boil, then turn the heat right down so the mixture is barely simmering, and cook for 5 mins until the raspberries break down. Stir well, but don’t mash them too much as the raspberries will break down in the heat.
Carefully pour the raspberry mixture through a sieve set over a large heatproof measuring jug. Stir in the lemon juice, then either top up with cold water or pour some away to ensure you have exactly 600ml total liquid. Drain the water from the gelatine leaves and squeeze out any excess before adding to the raspberry mix. Stir well until the gelatine has completely dissolved, then pour into your jelly mould (see tip below). Once cold, place in the fridge and leave overnight to set.
Turn the jelly out onto a large plate just before serving. Serve with a scoop of clotted cream or ice cream, and some raspberries.
Presentation tipsCreate a striking centrepiece for a dinner party by setting the jelly in a classic jelly mould, or go for a modern presentation by dividing the jelly between a mismatch of cocktail glasses and tumblers.