Onion is undoubtedly one of the most difficult things to leave out of your diet when you start with the Low FODMAP diet. Not so much so because you have to use onion in your dishes every day, but because it is incorporated into many things. It is included in many spices, soups, sauces, bouillons, meat and so on. You will be amazed at how many products secretly have onion or onion powder added just for the taste. Unfortunately, onion is also one of the classic products that are known to cause intestinal complaints. Personally, I have a lot of trouble with eating onion, which is why I do not do that anymore.
Fortunately, there are alternatives. The simplest alternative is to replace onion with spring onion. Spring onion, also called forest onion or salad onion, is a direct family of the onion. It is actually the samen plant. So it seems strange that you could eat it. But you do not eat the onion yourself; only the green part of the spring onion is Low FODMAP. The white part is very rich in FODMAPs. The reason why you are allowed to use the green part of the spring onion is that the sugar chains that are hard to digest have been converted by the plant into sugars that are easier to digest. This happens under the influence of sunlight. The same principle takes place in other vegetables of which you can only eat the green part in the FODMAP diet, such as leeks and endive.
When you use Spring Onion as a substitute you can just exchange it 1 on 1 in dishes. Spring onion is great to use for baking in, for example, olive oil as the basis for a recipe. But it is also good to eat raw in salads or with oriental dishes. It is advisable to cut small rings from the green of the onion. This way it gives more flavor.
A problem of every diet, including the Low FODMAP diet, is that it can be a lot more expensive than “normal” food. Onions are a lot cheaper than spring onions. But if you do a little trick, spring onion is actually cheaper than onion. So you can also save a lot of money on this aspect. Now I hear you think: how is that possible?
It is very simple: When you have fully used up the green of a bunch of spring onion for your dishes, cut the spring onion on the transition from the green to the white part (usually where the branches start). Do not cut too low, because then the trick will not work properly! Then put the cut bunch in a good layer of water in a glass so that the roots are under water. Put this glass in the sun somewhere in front of the window. After a few days you will see that the onions will begin to grow. And what is even better: only the green part grows! After a little over a week you can start using the green of the onion again. Simply cut the new green shoots to use in your recipes. If you replace the water in the glass once a week, a bunch of onion can last a long time in this way. If you put a few in glass this way, you always have enough spring onion for your dishes and it also saves money! Below you can see an example of spring onion that I have prepared this way myself. The left is 2 days after cutting, the right one is 9 days after cutting.
Besides spring onion there is another alternative, namely leek. Only the green part of leeks may be used. Leek can be used as a substitute in dishes that need processing or blending, such as soups. It becomes more difficult in sauces and pastas, because the green part of the leeks is rather stiff and tough (chewy). In addition, leeks have a very pronounced flavour, which is a bit like onion but also has its own character.
I do not use leek as a substitute for onion very often, but you can make delicious dishes with leek. You can also use a similar trick with leek as with the spring onion, only then you should actually plant them in the soil. Leek also has the capacity to grow green leaves for some time after planting, although this process is less quick than with the spring onion.
Finally, we have chives. Chives is an herb that has been used in western cuisine for years. I used to find it a delicious product to use in an omelet or egg salad. When I started the Low FODMAP diet, I discovered that it can also be used as an alternative to onion. Especially when making sauces or dishes that can do with slightly “spicier onion flavor”, chives are perfectly suitable. Chives are slightly sharper in taste than spring onion and leeks.
In addition, fresh chives are fine plant to put in the garden. The plant comes back every year in the spring and can become quite large. Dried chives is also for sale in the store. This is a lot less sharp in taste. I always have a jar of it in the cupboard, in case I accidentally have no spring onions or leeks or fresh chives anymore. The dried chives can then be used as an alternative to onion. It’s a bit of a last resort, but it works better than leaving out the onion altogether.
And now the surprise. You can secretly use onion, but not in the way you think. FODMAPs dissolve in water, so if you put onion in your recipes, then the whole recipe is filled with FODMAPs. There is no point in getting the onions out of it afterwards, the harm has already been done. but ….. FODMAPs do not dissolve in oil. That means you can bake onions in olive oil for a few minutes and then remove them from the oil. The taste of the onion is then infused into the oil. This trick is especially useful when you really need that specific taste of (red) onions or shallots in your recipe. In other cases I would advise to use spring onion, because it is a lot more practical.
You can also find ready-to-use onion oil in some stores. The same process as described above is used to get the taste into the oil.