If you’ve made Japanese curry before but find that it’s not thickening up like you expect, there are a few common reasons why this might happen and some easy fixes to try. In this article, we’ll go over the basics of how curry paste thickens, look at the most likely culprits for thinning out your curry, and provide solutions for how to adjust your recipe or technique to get the rich, luxurious texture you want.
How Does Curry Paste Thicken?
To understand why your curry might not be thickening, it helps to first look at what makes Japanese curry paste thicken in the first place. The thickening agent in Japanese curry roux blocks is starch – usually wheat flour or cornstarch. When the curry roux is heated in liquid, the starch granules absorb moisture and swell up. As it cools, this gelatinized starch sets into a thickened sauce.
So if your curry sauce isn’t getting nice and thick, it likely means the starch isn’t able to properly absorb liquid and gel. There are a few common reasons this can happen:
Not enough roux
The first thing to check is whether you used enough curry roux blocks for the amount of liquid in your recipe. Japanese curry blocks are concentrated paste, so you need to use enough to properly thicken all the extra liquid you’re adding. Here’s a general guideline for roux-to-liquid ratios:
| Liquid | Roux Needed |
|---|---|
| 4 cups | 1 block (1.76 oz/50g) |
| 6 cups | 2 blocks (3.5 oz/100g) |
| 8 cups | 3 blocks (5.3 oz/150g) |
If you’re working with a large volume of liquid but didn’t increase the roux accordingly, the starch may get diluted too much to properly thicken. Try reducing the liquid or adding more roux.
Not simmering long enough
The starch in the roux needs sufficient time simmering in the liquid to fully absorb moisture and swell. If your curry sauce is still thin, try letting it simmer longer – up to 30 minutes after adding the roux blocks. This gives the starch granules more opportunity to fully gelatinize.
Adding roux at wrong time
For best thickening, you need to add the curry roux once the liquid is already simmering. Adding it too early when the liquid is still cold prevents the starch from absorbing moisture properly. Wait until your curry base of onions, carrots, potatoes etc. is simmering then add the blocks and keep simmering.
High heat
Too high heat can also interfere with thickening. Boiling or high heat can disrupt the starch gel formation, resulting in a thinner sauce. Maintain a gentle simmer after adding roux blocks. If the curry is boiling rapidly, turn down the heat to allow it to thicken.
Added ingredients diluting the curry
Adding extra liquid ingredients after the roux will thin out your curry sauce. Ingredients like stock, milk, coconut milk, or Worcestershire sauce can all undermine thickening if added after simmering the roux. Avoid adding extra liquids – only add solid ingredients once your curry has reached the desired thickness.
How to Fix a Thin Japanese Curry
If you notice your Japanese curry sauce still seems too thin after simmering with the roux, don’t worry – there are some easy ways to fix it:
Simmer longer
Give the curry more time over low heat for thickening to occur. Let it simmer very gently for up to 30 minutes, stirring occasionally.
Mix a slurry
Make a slurry by mixing 1 tablespoon of starch (cornstarch or flour) with 1-2 tablespoons of water. Slowly stir this into the simmering curry sauce until well incorporated. Let simmer 5 more minutes until nicely thickened.
Add more roux
For a very thin curry, you can boost thickening power by adding more curry roux blocks. Use increments of 1/2 block at a time until desired consistency is reached.
Finish with a beurre manié
A beurre manié is a paste of equal parts butter and flour mashed together. You can thicken the curry at the very end by whisking in small amounts of this paste until the curry coats the back of a spoon.
Tips for Making the Perfect Thick Japanese Curry
Once you know the science behind thickening and what causes thinning, it becomes easy to tweak your technique to get that ideal rich, luxurious texture every time. Here are some useful tips:
Use the right curry roux
Not all Japanese curry blocks are equal. Some contain more thickening power than others. Good reliable brands like S&B Golden Curry and Vermont Curry deliver consistent thickening.
Cut vegetables small
Cutting ingredients like onions, carrots and potatoes into smaller pieces means they’ll cook faster and release more starch to aid thickening.
Add potatoes and carrots before roux
Add starchy veggies like potatoes and carrots before the roux and simmer until very soft. This helps thicken the sauce.
Limit added liquid
Avoid thining the curry by adding extra liquid ingredients. Hold off adding milk, stock, juices, etc until after simmering the roux.
Skim off excess fat
Fat from meat and oils can inhibit thickening. Use a spoon to skim off excess fat before adding roux.
Sprinkle flour on meat
Coating meat in a dusting of flour before browning helps release extra starch for thickening the curry.
Adjust heat as needed
Maintain a gentle simmer, reducing heat if it starts boiling rapidly. This prevents the sauce from thinning out.
Finish with beurre manié if needed
Have some beurre manié (butter-flour paste) handy to stir in right at the end for last minute adjustments.
Conclusion
With a little tweaking of ratios, timing, and technique, you can easily get your Japanese curry to achieve that ideal rich, luxurious thickness. Now that you know the science behind what makes curry sauce thicken and thin out, you can troubleshoot your recipe and adjust as needed. Follow the tips above for ensuring perfect thick curry every time.