Take the butter out of the refrigerator and let it sit on the kitchen counter. While the butter reaches room temperature, rinse the parsley thoroughly in cold water so that both the stems and leaves are free of soil. Subsequently, clean the Nasturtium flowers, and chop both them and the parsley finely. Mix the flowers and parsley with the softened butter so the herbs are evenly distributed. Add more parsley or more flowers if you want greener or redder butter. Season the butter with salt before rolling it into a ball, which is then placed on wax paper. Fold the paper around the fresh butter and roll it into an elongated sausage shape. Seal the ends of the paper and refrigerate the butter for at least 30 minutes. After a time in the refrigerator, it will be firm enough to cut into nice slices and serve.  

Shelf Life and Storage

• You can easily make the fresh herb butter with parsley and Nasturtium well in advance. If you want to serve it to your guests, you can advantageously make a large portion the day before. As long as you store it in an airtight container, it has a shelf life of up to 14 days in the refrigerator.
• The butter can also be frozen without affecting the parsley flavor, and the color from the Nasturtium does not diminish after a trip to the freezer.
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• The delicious, colorful butter is a lovely, summery accompaniment to the many grilled dishes the season offers. I serve it along with grilled asparagus, corn on the cob, and other crispy vegetables, as it is a nice alternative to sauce. Therefore, you should not skip serving the ice-cold butter with fresh, new potatoes or putting a good dollop in a baked potato.
• The intensity of the parsley also suits meats, and especially steaks and fish enjoy the butter's company. If simplicity is key, I also love eating my herb butter on good bread.
• Both Nasturtium and parsley can be harvested well into the fall, and this perfectly coincides with the first root vegetables coming into season. I like to whisk the parsley butter into Jerusalem artichoke puree and mashed potatoes or celery root mash to bring out a beautiful color, but certainly also for the sake of flavor.