A blooming onion is a popular appetizer found on many restaurant menus. It consists of a large onion that is cut to open up into “petals” and then deep fried, resulting in a crunchy, onion-flavored bloom shape. But before frying, blooming onions are usually soaked in water first. There are a few important reasons why this soaking step is included when making blooming onions.
To Soften the Onion
One of the main reasons to soak a blooming onion in water before frying is to help soften and partially cook the onion. Onions have a crisp, raw texture when completely uncooked. Frying works best when the onion has been softened slightly first.
By soaking the onion “bloom” in water ahead of time, the water starts breaking down some of the cell structures in the onion that give it that crunchy texture. This allows the onion to cook more quickly and evenly when fried.
If you were to fry a completely raw, unsoaked onion, the outside would likely burn before the inside layers got fully cooked and tenderized. Pre-soaking allows the inside and outside of the onion to cook at a more equal pace.
To Reduce Harsh Flavors
Soaking a blooming onion can also help mellow some of the more pungent, harsh sulfur compounds found in raw onions. Onions contain amino acids and sulfides that give them their signature bite and ability to make you tear up when you cut them.
While these compounds provide important flavor, they can be overpowering in a raw onion. Soaking the onion allows some of these harsh notes to leach out into the water. This provides a more mellow, balanced, sweet onion flavor when cooked.
To Make the Onion Easier to Handle
The soaking step also prepares the onion to be handled for frying by making it more pliable and flexible. Raw onion is quite brittle and stiff. Soaking an onion bloom softens the structure so the petals can open up without cracking or breaking off.
The added moisture also weighs the onion down so it stays open and doesn’t try to close back up when placed in the hot oil. This allows the onion to fry up into the desired flower shape.
To Clean and Remove Excess Starch
Soaking a blooming onion in water can also help remove any dirt or debris clinging to the onion layers from the cutting process. The water helps wash away any visible dirt particles.
In addition, soaking helps remove some of the starch from the onion that would otherwise soak up extra grease when fried. Letting the onion bloom sit in water allows the starch to dissolve so less of it remains on the onion itself.
To Add Flavor Via Brining
Rather than just using plain water, some recipes call for soaking blooming onions in a saltwater brine before frying. This allows the salty brine to infuse into the onion, seasoning it throughout.
The salt also helps draw out more moisture from the onion, further reducing any harsh sulfur compounds. This is similar to soaking onion rings in buttermilk or a brine solution to improve flavor before breading and frying them.
Any of your favorite herbs, spices, vinegars, or other flavors could be added to the soaking brine to further boost the flavor of the blooming onion from the inside out.
To Increase the Onion’s Absorption
As the onion soaks, it becomes more porous as the water loosens up cellular structures. This causes the onion to act like a sponge, allowing it to better absorb oil or batter when frying.
Rather than oil just coating the outside, a soaked onion can soak up more oil into all the layers, helping it to fry up extra crispy and evenly browned. The same goes for batter or breading adherence.
Any seasonings added to the batter or flour will also penetrate the onion better after soaking to provide more flavor. So soaking leads to a more flavorful blooming onion in the end.
To Partially Cook the Onion
Depending on the soaking time and water temperature, soaking can partially pre-cook the blooming onion.
Warm water will soften the onion faster than cold water due to increased enzyme activity at warmer temperatures. And soaking for an extended time will allow more thorough water penetration into the onion.
This precooks the onion somewhat similarly to blanching or parboiling veggies before finishing cooking them. So less frying time may be needed to finish off a blooming onion that has soaked for a while versus one straight from the cutting board.
Optimal Soaking Time for Blooming Onions
When it comes to soak times, sources recommend anywhere from 30 minutes up to several hours of soaking for blooming onions specifically. Here are a few general soaking guidelines:
- 30 minutes – 1 hour: Good for crisp-tender onion
- 1-2 hours: Allows more flavor and starch removal
- 3 hours or more: Thoroughly softens and precooks onion
The longer you soak, the more the onion will cook through and the less frying time you may need. Shorter soaks around an hour simply soften and season the onion to allow it to bloom without breaking when frying.
Water Temperature for Soaking
The temperature of the water also impacts the effects of soaking. Here are some tips:
- Cold water: Preserves crispness, doesn’t precook onion
- Room temperature water: Softens onion moderately
- Warm water: Speeds softening and precooking
Cold soaks are best for blooming onions you want to fry into very crispy and lightly cooked onions. Warm soaks quickly break down the onion more for faster frying.
Other Important Soaking Tips
- Use plenty of water to submerge onion
- Weigh down onion bloom to keep it immersed
- Swish onion in water periodically to evenly soak
- Pour off starchy water after soaking and pat dry
Following these simple tips ensures the blooming onion soaks properly for the best results when frying.
Conclusion
Pre-soaking a blooming onion before deep frying is an important step that leads to better flavor and texture. The water hydrates and softens the onion, allows harsh compounds to leach out, makes the onion more pliable for frying, and leads to better absorption of oil and batter.
Optimal soaking times are generally 1-3 hours, with warmer water speeding the softening and precooking process. Taking the time to soak blooming onions correctly results in restaurant-quality appetizers with caramelized, tender layers.
| Soaking Time | Effects on Onion |
|---|---|
| 30 minutes – 1 hour | Crisp-tender onion |
| 1-2 hours | More flavor and starch removal |
| 3 hours or more | Thoroughly softens and precooks onion |
References
[1] Blooming Onion. (n.d.). Retrieved from https://en.wikipedia.org/wiki/Blooming_onion
[2] J. Smith, Blooming Onion Recipe Secrets. Food Network. Retrieved from https://www.foodnetwork.com/fn-dish/news/2015/07/bloomin-onion-outback-steakhouse-recipe
[3] Outback Steakhouse Bloomin’ Onion Recipe. CDKitchen. (2019). Retrieved from https://www.cdkitchen.com/recipes/recs/2184/Outback_Steakhouse_Bloomin039Onion100912.shtml
[4] Blooming Onion. The Spruce Eats. (2020). Retrieved from https://www.thespruceeats.com/blooming-onion-recipe-995566
[5] How to Make a Blooming Onion Appetizer. Delish. (2020). Retrieved from https://www.delish.com/cooking/recipe-ideas/a28414280/blooming-onion-recipe/