Fittingly, Walsh uses a bacteria known as Lactobacillus Bulgaricus. She got her culture from Bulgaria and keeps it alive the same way people do back home — by using a small portion of her last batch as an ingredient to make the next.
"Lactobacillus Bulgaricus destroys most of the bad bacteria which live in our bodies and which cause bacterial infections," she explained. "It also helps people with gastrointestinal problems, lung diseases, and even cures dairy intolerance."
She also makes yogurt in the traditional Bulgarian way.
"I manually boil the milk, and do everything by hand. I wouldn't switch to using machines, because the whole process is very sacred and special to me. It also brings totally different results," she explained.
The quality of milk is crucial when making Bulgarian yogurt in particular. As Walsh's grandma told her, "If the milk is not good, your yogurt will never set; it will stay liquid." Walsh added that the best results come from milk that isn't pasteurized or processed. Full fat milk is also preferred.
Once the culture has been put into a pot with milk, the most important step in making the yogurt is to leave it absolutely still for 10 to 14 hours.
"The slightest movement will prevent the bacteria from doing its job, and the milk will not turn to yogurt. Because of this, I like to think that homemade Bulgarian yogurt is a peaceful food," she said.
You can leave out sweeteners when making healthy natural yogurts at home; but when craving something sweet, brown sugar, honey or maple syrup are good options to add a bit more flavor.
"Here's a little tip for beginner yogurt makers: both sugar and honey add thickness to the texture, so if you have a sweet tooth and you're struggling to get a solid yogurt, add something sweet. I like maple syrup as a healthy sweetener," said Walsh.
Yogurts are good to enjoy on their own, but if you make too much the left-overs can be used in both sweet and savory dishes.
In Bulgaria, many traditional foods contain yogurt. Some breads, pastries, cakes and puddings are made with yogurt rather than milk.
An all-yogurt based traditional soup called Tarator is a favorite starter, especially in summer. It is made with cucumbers, garlic, walnuts, dill and yoghurt.
"One of the types of Bulgarian yogurt I make has a cottage cheese texture. I use it as salad dressing, or as a healthy substitute to butter on a piece of bread," Walsh said.
The shelf-life of natural homemade yogurt varies by season and temperature. Yogurt made with live bacteria like Lactobacillus Bulgaricus has to be kept refrigerated, or it will go off within three days in winter and two in summer. If stored at the right temperature, it will be at its best for about two to three weeks.
