I just made the recipe below for slow cooker dal and there is quite a bitter flavor. I'm wondering: - what ingredient would cause this bitterness and why? - is there something I can add to counter the bitterness?

2 teaspoons whole cumin seeds
2 teaspoons whole mustard seeds
1 teaspoon whole fennel seeds
2 cups split red lentils, rinsed
5 cups water
1 (15-ounce) can diced tomatoes
1 medium onion, diced
1-inch piece fresh ginger, peeled and finely grated
1 tablespoon ground turmeric
1 bay leaf
1 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
Fresh cilantro leaves, for serving (optional)
Jasmine rice, for serving

Add the cumin, mustard, and fennel seeds to a small sauté pan, and place on the stove over low heat. Toast the seeds, using a wooden spoon to stir frequently, until fragrant, 3 to 4 minutes.

Add the toasted spices, lentils, water, tomatoes, onion, ginger, turmeric, salt, and pepper in the bowl of a 6-quart slow cooker. Stir together. Cover the slow cooker with the lid, then set to low and cook for 4 to 6 hours, or high and cook for 2 to 3 hours, until most of the liquid has been absorbed and the lentils are soft. Stir before serving.

  • 2
    This suggests that mustard seeds might have that effect. Personally I don't know for sure. cooking.stackexchange.com/q/73941/34242
    – Ecnerwal
    Nov 7, 2017 at 4:14
  • Nothing in there jumps out at me, it's possible you over-toasted the seeds.
    – GdD
    Nov 7, 2017 at 9:48

4 Answers 4


In dal recipes I have made, the lentils and tempering are cooked separately, then combined later. They generally begin by toasting spices (careful, mustard pops, but that is what you want), then caramelizing thinly sliced onion in the spices. This brings out the sweetness of the onion, which can offset the bitterness of some of the spices. Once the lentils are cooked, the tempering (onion and spices) is added and the seasoning is adjusted.

  • So I think my first question was answered through comments, thank you: it's probably the mustard seeds (I probably browned them too much) that caused the bitterness. But I'd still like an answer to my second question: are there any culinary suggestions for hiding/eliminating the bitterness?
    – Arlo
    Nov 7, 2017 at 16:57
  • @Arlo my response is "a culinary suggestion for hiding/eliminating bitterness." Often ingredients that are naturally sweet, or have their sweetness heightened (as in caramelizing onions), do just that.
    – moscafj
    Nov 7, 2017 at 17:03
  • I'm sorry for the confusion - I think I wasn't clear. I'm looking for a culinary suggestion for the batch I made yesterday, i.e., what can I add to make it edible. I do appreciate your suggestions for future dal that I make. I think my mistake was to think I could just dump everything in a slow cooker and it would work!
    – Arlo
    Nov 7, 2017 at 20:19

Mustard seeds are seldom used toasted+powdered in indian style recipes - more commonly they are usually quickly fried in high-eat oil or ghee (popping is supposed to happen - just don't keep a high heat going after that has happened...), either as a very first step when a sauce is built, and/or added in the hot oil to a boiled dish (like your dal) only a few minutes before it is finished.

In both cases, other spices that benefit from sauteeing (eg curry leaves, garlic, fennel seeds, hing, cumin, dried peppers (capsaicin vapors, be careful) ) can be added in the same oil, usually at a lower heat after the mustard has popped.

Also, a bitter/stodgy/watery taste in indian recipes sometimes just means you need to add some salt, sugar or acid (lime juice is always a good idea if acid is needed - do not overheat it!) - some of the spices can give confusing impressions that suggest the dish is salty when it is not.

Also, fresh cilantro can taste rather bitter to some people - a little staler cilantro even more.

  • thank you so much. You helped me rescue an inedible Dahl made with tinned lentils (all I could get due to supply chain issues). It went from gag worthy to amazing by following your steps. ❤️
    – MegLeigh
    Feb 5, 2022 at 3:42

I have just had the same problem with a lentil dahl - and it's not the first time. Now I know that I have been over-cooking the spices. This is the fix I am about to try: Step 1 Taste the curry sauce and determine the level of bitterness as well as the underlying flavors. Highly bitter curries need more of the bitterness-minimizing elements.

Step 2 Add salt and sugar to the curry sauce in equal portions, a generous pinch or dash at a time, until the flavor is more balanced. Salt brings out the natural sweetness of curry spice and the sugar will help balance the saltiness and bitterness. Do this two or three times and then go on to the next fix if it's still bitter. Use palm sugar, cane sugar or other sweeteners appropriate for the curry, if you prefer. Table salt, kosher salt or salty fish sauces can work as the salt elements.

Step 3 Blend in coconut milk, coconut cream, yogurt or sour cream, 1/4 cup at a time, tasting after each addition. If after three additions, the curry is still bitter, the curry needs more items added.

Step 4 Add 1/4 teaspoon of ground coriander seed or root to the curry sauce and the juice of one lime. Blend this together well and taste it. If the curry is still too bitter, it is likely that the curry blend is too overcooked to be salvaged.

  • I have just gone through the above process with my seemingly horribly bitter dahl soup. HOWEVER, I followed the steps above right through to the coconut milk and each time I added an ingredient I could taste an improvement - to the point, in the end, that my soup is now actually DELICIOUS! Whoop whoop. A great learning experience too
    – Helen
    Jan 13, 2018 at 20:31

Tumeric and mustard seeds both have a dry bitterness to them. This is probably where the taste you describe comes from. If you dislike it reduce or omit these two spices.

The fennel and cumin could also probably be cut in half. If you temper the spices it concentrates the flavours. If you like heavy seasoned foods then go for it but that is probably a stronger spice profile than most people in the west are comfortable with.

Ps. Always add salt to your legumes at the very end when everything is cooked thouroughly. Otherwise you get cooked and hard legumes. Which is unpleasant.

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