I made nasturtium capers earlier this year and enjoyed them immensely. For those interested in doing this be sure to find the nasturtium seed pods still attached to the stems under the foliage, picking only the young pods that are still green and soft--not yellow.
Here is the basic method for a brined nasturtium caper:
Brine the soft green nasturtium seed pods by bringing salt and water to a boil in a small saucepan. Put the nasturtium pods in a half-pint sterilized glass jar and pour the boiling brine over them. Cover and let them soak at room temperature for 3 days.
Then pickle the pods by draining the brined pods in a fine sieve and putting them back in the jar. Bring vinegar, sugar, bay leaves and thyme to a boil in a 1-quart saucepan. Pour the boiling vinegar mixture over the seed pods and let cool. Cover the jar and refrigerate for 3 days before using. They keep up to 6 months in the refrigerator if covered in the vinegar.