1. Split the vanilla pod lengthwise into two halves and scrape out the seeds.
2. Mix scraped seeds with sugar, water and vinegar in a kettle. Cook for a few minutes. Then add the rosehip.
3. Simmer for about 20 minutes, adding hazelnuts at the 15-minute mark.
4. Pour the mixture into clean, scalded jars. Place the lid on.
Store spread in a cool, dark place.