I recently took a fermentation workshop at Santropol Roulant. The older I get, the more I feel I’m slowly fermenting — more pungent at times, also more likely to be agitated. The word derives from the Latin for “boil over.” A workshop seemed appropriate.

While Santropol Roulant is known for its meals-on-wheels service, it does offer occasional cooking classes. As I stood there chopping cabbage, I thought about how many foods were processed before there was refrigeration. Fermenting has always been a good way to extend the harvest.

Fermenting happens naturally as bacteria convert carbohydrates or sugars in a food into lactic acid, usually in the absence of oxygen. This gives off a sour taste and smell.

Yeasts work similarly by converting flour and water into a sour dough and potatoes, grains or fruit into alcohol. Yogurt is a fermented food, as is kefir, a fermented milk drink common in Middle Eastern cultures. Thai fish sauce is a fermented food, as well as the tea-like, slightly effervescent drink, kombucha.

Brining, I learned, is fermenting with highly salted water. Sauerkraut can be made just by rubbing sliced cabbage leaves with salt; it will make its own brine. Pickling can include vinegar. The popular Korean condiment kimchi, of which there can be many types, is a kind of brined kraut. Traditionally it was made in jars and buried in the ground. Now it can be made in a few days and keeps refrigerated for months. Refrigeration slows down the fermentation.

The acid in fermented foods gives zest to meals and balances the richness of fat. For example, mixing vinegar or lemon juice with oil makes a tastier salad dressing than using either of them alone. A hot dog gets more nutrition and a flavour boost with a topping of sauerkraut. Ditto for a hamburger with a pickle on the side, or brisket with horseradish.

An easy way to get into making a fermented dish is with a daikon radish. These are large, cucumber-sized, mild tasting radishes common in many supermarkets and Asian food stores.

Clean and peel the radish. Cut it into bite-sized cubes or finger-sized spears. Mix these with a teaspoon of kosher or non-iodized salt in a glass bowl. Let this sit for a half hour as it marinates. If you want, mix in a half teaspoon each of grated ginger and finely minced garlic, or some chili flakes for a spicier kick.

Sterilize a clean one litre or quart jar by putting it into boiling water for a minute; alternately half-fill the jar with water and bring it to boil in a microwave oven. Empty the jar and let it cool. To make a brine, dissolve two tablespoons of salt in two cups of water. You can tell if the brine is salty enough by floating an egg in it. If it doesn’t come to the top, add more salt.

Pack the radish and its liquid into the jar. Add enough brine to cover the radish. Cover this with a clean cabbage or lettuce leaf. Weigh this down with something small but heavy such as a smaller sterilized jar filled with water. All of the radish must be submerged in the brine. Cover the jar loosely so that gases can escape as it ferments and let it sit in the coolest part of the kitchen for 4 or 5 days. You can taste it as it ferments. When it is to your liking, remove the weight, put a lid on the jar, and keep it in the refrigerator.