Put the egg yolks and 200g of the caster sugar in a bowl. Scrape the vanilla seeds from the pod, add to the bowl, and mix together by hand with a whisk. Bring the cream and the vanilla pod to the boil, add to the egg mixture, and mix thoroughly.
Divide the custard into two halves, discarding the pieces of vanilla pod. Cool one half rapidly over a bowl of ice, and chill in the fridge for 10-15 minutes.
Preheat the oven to 170°C/gas 3. Place the berries in a saucepan with the remaining caster sugar and the lemon juice. Poach gently for 3-4 minutes, then place the berries in the bottom of four 12cm moulds or cups, and pour the unchilled custard on top.
Place in a roasting tin, pour in warm water to come halfway up the sides of the moulds, then bake au bain marie for 30 minutes or until the custards are just set - they should wobble like a jelly when tapped. Remove from the oven, leave to cool, then put in the fridge. Keep the oven on.
Make the crumble. Put all the ingredients into a food processor and blitz quickly. Spread out on a baking sheet and bake at the same temperature as the custards for 10-15 minutes until golden. Leave to cool.
Make the ice cream. Mix the chilled custard and lavender honey together, churn in an ice cream machine until thickened, then decant into a container and freeze and freeze.
Top the chilled berry custards with the crumble and ice cream.