Onion Koji
A sweet, mellow fermented onion paste that works as a substitute for consommé in toddler recipes!
Onion koji is a natural seasoning made by fermenting blended Japanese (tamanegi) onions with rice koji and salt. It’s rich in natural sugars, enzymes, and umami — giving it a deep, caramelized-onion flavor without having to sauté a thing.
Onion Koji Recipe
Ingredients:
100g dried rice koji
300g yellow or white onion (around 2 medium sized or 1 large), peeled & chopped
15g sea salt (around 1 heaping tablespoon) - I used pink Himalayan salt, for this batch, hence the pink tint
📌 You can use sweet onions or Japanese tamanegi for best results. Avoid red onions (too sharp) or green onions (too moist).
Instructions:
Prep the onions
Roughly chop the onions and blend until smooth in a food processor or blender.Mix
In a clean glass or ceramic bowl, mix the onion purée with the rice koji and salt. Stir until fully combined — it should be thick, a bit grainy, and slightly juicy.Ferment
In a clean glass or ceramic bowl, mix thTransfer to a clean jar. Cover loosely (with a cloth or a lid set ajar) and ferment at room temperature for 5–7 days, stirring daily. It should start to smell sweet and slightly funky — like caramelized onions meets miso. onion purée with the rice koji and salt. Stir until fully combined — it should be thick, a bit grainy, and slightly juicy.Store
After fermentation, seal, label with date, and store in fridge. Keeps up to 2 months.
How to Use Onion Koji:
Stir into rice porridge, pasta sauce, or soups
Mix with minced meat for koji meatballs
Spread a little into a veggie stir-fry
Use as a natural sweet-savory base for mama’s curry, risotto, or bolognese
Note for Toddlers:
Onion koji is low in salt (5% of total weight) and high in natural sweetness. It’s suitable for babies 10 months and up, in small amounts, especially if they’ve already tolerated onions. Always start with a small taste and mix it well into cooked foods.
Ingredients:
In Hong Kong, I purchase tamanegi from Waraya or Citysuper.
