Kefir overnight oats

By Nik, founder of 東歐嚴選｜kefir.link and former chef · Updated 2 November 2026

Stir rolled oats into milk kefir at night, tip frozen mango on top, and a cold breakfast is waiting in the fridge by morning. The oats soften without any cooking, and the kefir makes them creamy with a gentle tang.

It began as a Swiss doctor's apple supper

Overnight oats became popular in Britain and America in the 2010s, but the idea goes back to Switzerland around 1900. A Swiss doctor served his patients oats soaked for 12 hours in water, mixed with grated unpeeled apple, lemon juice and condensed milk and topped with nuts, as an evening dish. It became Swiss muesli, which today is eaten mostly at breakfast, often with yogurt or milk in place of the condensed milk.

Why kefir and rolled oats get along

Milk kefir is thicker than milk but thinner than yogurt, so it does the work of both, and the oats end up neither runny nor stiff. It keeps fermenting in the bottle, so an older bottle makes sourer oats; a teaspoon of honey in the morning softens the tang. Rolled oats turn soft with a little chew, instant oats go softer and can turn mushy, and steel-cut oats stay hard unless cooked first. For thicker oats add a few more flakes, and for looser ones a splash more kefir.

Mango from the freezer, crunch in the morning

Frozen mango goes straight from the freezer onto the oats and is soft by morning. Frozen diced Irwin mango is easy to find in Taiwanese supermarkets, and sliced banana is a good swap. Strawberries and blueberries with a pinch of cinnamon make a different jar. Keep nuts out of the soak and scatter them on at breakfast so they stay crunchy; steamed diced sweet potato is good added then too.