Onion powder is a pantry staple that brings deep, savoury sweetness to rubs, soups, and sauces without the tears or the prep. Making your own at home in the UK is surprisingly simple, and the result is far more aromatic than most shop-bought jars. This guide walks you through drying and grinding onions into a fine, golden powder that keeps for months.
Ingredients
- 2 large onions (about 400 g / 14 oz), any variety
- Optional: 1 tsp flaky sea salt (if making seasoned onion salt)
Instructions
- Preheat your oven to the lowest setting, ideally 60°C (140°F) or the “keep warm� setting. If your oven only goes to 80°C (175°F), that works too—just keep a close eye on the onions.
- Peel the onions and slice them as thinly as possible, using a mandoline or a sharp knife. Aim for uniform 2–3 mm slices so they dry evenly.
- Spread the slices in a single layer on a baking tray lined with parchment paper. Do not overcrowd; use two trays if needed.
- Place the tray in the oven and leave the door slightly ajar (use a wooden spoon to prop it open) to let moisture escape. Dry for 3–4 hours, turning the slices every hour, until they are brittle and snap cleanly when bent. They should not be leathery or flexible.
- Remove the dried onions from the oven and let them cool completely for about 15 minutes. They will crisp up further as they cool.
- Transfer the dried slices to a spice grinder or high-speed blender. Blend in short bursts until you get a fine powder. If you want an ultra-fine texture, sift the powder through a fine-mesh sieve and re-grind the larger bits.
- If making onion salt, mix the powder with the flaky sea salt and store separately from plain onion powder.
- Store the powder in an airtight jar in a cool, dark place. Use within 6 months for the best flavour.
Tips
- Use a dehydrator if you have one: a food dehydrator at 55°C (130°F) for 6–8 hours gives even, consistent results and frees up your oven. Just ensure the onions are completely brittle before grinding.
- Watch the oven temperature: if the onions brown instead of staying pale, your oven is too hot. Browning is fine for flavour, but it will make the powder slightly bitter and darker.
- Grind in small batches: overloading a blender can create heat, which causes the powder to clump. Work in 1-cup batches and let the powder cool before storing.
- Store in a labelled jar: homemade onion powder doesn’t look like the commercial version—it’s often coarser and more fragrant. Label it with the date so you know when to use it by.
Serving Suggestions
Use your onion powder to season roasted vegetables, sprinkle over popcorn, or stir into sour cream for a quick dip. It’s also excellent in homemade burger patties, meatballs, and dry rubs for chicken or pork. Add a teaspoon to soups, stews, or gravy for an instant savoury boost.
Variations
- Smoked onion powder: use smoked onions (grill them first until charred, then dry) for a barbecue-style twist.
- Garlic-onion blend: dry sliced garlic cloves alongside the onions and grind together for a ready-made all-purpose seasoning.
- Onion salt: mix 2 parts onion powder with 1 part fine sea salt for a seasoned salt that’s perfect for chips and fries.
Storage and Reheating
Store the powder in an airtight glass jar away from light and heat. It will keep for up to 6 months at room temperature, but for longer storage, you can freeze it in a sealed bag for up to a year—just let it come to room temperature before opening to avoid clumping. There’s no reheating needed; simply add the powder directly to your dishes. If it develops any moisture or clumps, spread it on a tray and dry it in the oven at 60°C (140°F) for 30 minutes.
Frequently Asked Questions
Can I use a microwave to dry onions? Yes, but it’s tricky. Place sliced onions on a microwave-safe plate and heat in 30-second bursts at 50% power, checking after each burst. It can take 10–15 minutes, and the onions may cook unevenly. The oven or dehydrator is more reliable.
Why is my onion powder clumping? Clumping happens when the powder absorbs moisture from the air. Make sure the onions are completely dry before grinding, and store the powder with a silica gel packet or a few grains of rice in the jar to absorb humidity.
Can I use red onions or shallots? Absolutely. Red onions give a milder, slightly sweeter powder; shallots produce a more delicate, garlicky note. Adjust the drying time if the slices are thicker.
How much fresh onion equals 1 teaspoon of onion powder? One teaspoon of onion powder roughly equals ½ cup of chopped fresh onion. For recipes, start with less and adjust to taste.
Is homemade onion powder safe to use in canning recipes? No, do not use homemade onion powder in home canning. The powder’s density and moisture content are not standardized, which can affect the safety of canned goods. Use commercial powder for canning, or simply add it to dishes before serving.
Why is my powder bitter? Bitterness usually comes from overcooking the onions during drying—if they brown too much, they develop a burnt taste. Also, if you grind the powder too long, the heat can scorch it. Keep the oven low and grind in short pulses.
Related
- Onion Powder to Onion: Easy Substitution Guide
- Corned Beef and Cabbage: Step-by-Step
- Granulated Onion Powder Uses: 5 Easy Ways
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