How Far to Cook Them Down (and How to Tell)
Okay, so this is the lesson where a lot of people get nervous, because I'm about to tell you the timing on the recipe card is basically a suggestion. Onions don't read the recipe card. They just don't.
Here's the actual question you're answering in this lesson: when do the onions stop being "raw onion with some heat applied" and start being "the base of a curry." Those are two different things, and the difference isn't really about minutes. It's about what's happening in the pan.
What you're going for
For most curries and dal, you want your onions cooked down until they're soft, golden, and starting to break apart at the edges. Not caramelized-for-French-onion-soup dark. Not raw-crunchy-still-white either. Somewhere in the middle, and honestly that middle is a wider target than people think.
I'll give you three checkpoints instead of a timer.
Checkpoint one — translucent. This happens fast, five to seven minutes on medium heat, and the onions go from opaque white to see-through-ish. They'll smell sweet, not sharp. If your eyes were watering when you cut them, that smell is gone by now. This is the stage a lot of jarred-sauce recipes stop at, honestly, and it's fine, it's just not where we're going.
Checkpoint two — golden and softening. Another five to ten minutes past that. Color shifts to light gold, edges get a little ragged, and they start sticking to the pan a bit between stirs. This is usually where I add my ginger-garlic if I haven't already, because the onions are soft enough to actually mingle with it instead of just sitting next to it.
Checkpoint three — the one we actually want. Deep gold, almost light brown in spots, and when you press a piece with your spoon it kind of collapses instead of holding its shape. The whole pan smells different than it did ten minutes ago — deeper, less sharp, a little sweet. This usually takes 15-20 minutes total from when you started, sometimes longer depending on your stove and how much onion is in the pan. Ours runs a little different up here too — that dry air can pull moisture out of things faster than you'd expect, so don't be shocked if your onions look further along than the clock says they should be. Trust what you see over what the clock says.
How to actually tell, pan-side
Stop stirring for thirty seconds and look at the bottom of the pan. If there's a brown film building up (not black, not burnt-smelling, just brown), that's good — that's flavor. Scrape it up into the onions next time you stir. If you're getting black bits and a burnt smell, your heat's too high. Turn it down. This isn't a race and there's no bonus points for speed.
Texture is actually a better clue than color for a lot of people. Push a piece of onion against the side of the pan with your spoon. Early on it resists, holds its shape. By the time you're done, it should just give. Almost mushy. That's it. That's the tell.
A confession about my own kitchen
I'll be honest, I don't actually time this step anymore. I used to, and I think that made me worse at it, not better, because I'd pull the onions off the heat the second the timer went off instead of looking at the pan. Now I just cook until they look and smell right and it's been more reliable, which I realize isn't a very satisfying instruction to give a beginner. So: use the checkpoints above until your eye gets trained, and then trust your eye.
Which — this is the same thing I tell my son Jesse about, weirdly. He won't touch a vegetable most places in our house, but he'll eat the cauliflower-and-pea curry I make, and I genuinely think part of it is that the onions are cooked all the way down so there's no raw onion bite anywhere in the dish. No sharp edge to object to. I've never asked him directly why he eats that one and not, say, roasted broccoli, because I'm half afraid if I examine it too closely the whole thing stops working. Some kitchen magic you just don't poke at.
The opinion part
If you only remember one thing from this lesson: don't rush this step and don't skip it. Undercooked onions are the single biggest reason a home curry tastes "off" compared to a restaurant one — people get impatient, the onions are still a little raw and a little sharp, and no amount of spice fixes that underneath. This is the unglamorous fifteen minutes that makes everything after it work. It's not blooming spices, which I already told you is the real heart of the thing, but it's close.
A quick caution
Onions release a lot of moisture early on and then that moisture cooks off, which means the oil starts spitting more as things go along. Keep the heat at medium, not high, and don't walk away and leave a toddler or a curious dog anywhere near that stove. I learned that lesson with turmeric and Lincoln's hands, not with hot oil, but the principle's the same — small kids and hot pans don't mix, and it only takes a second.
Before next time
Cook down a plain batch of onions with nothing else in the pan, just to watch all three checkpoints happen without worrying about anything else going on. Ten minutes, no recipe pressure, just watch.