Takana-zuke is available at most supermarkets across Japan. It’s also often sold at street markets as regional specialties, in department stores and attsukemono (pickle) shops. Takana-zuke keeps for weeks in the refrigerator, even after opening, so you’ll have plenty of time to let the experiments continue. I recently tried it as an addition to artichoke spinach pasta and found it added a pleasant, mild tartness. I even tried a spoonful of it over cheese toast, and it worked perfectly.