Anyone cooking Indian food in batches learns quickly that dal keeps and a dry vegetable dish does not. The reason is structural, and it holds across almost every version of both.
Dal has no structure left to lose
Pulses are cooked until they collapse, so the dish is already a uniform suspension. There is no distinct texture that storage can degrade.
Reheating thickens it as more water evaporates, but that is corrected with a splash of water in seconds.
Nothing in the dish depends on a piece staying separate from another piece, which is the condition that makes most food deteriorate.
Why the flavour actually improves
Time allows the spice compounds dispersed in the fat to distribute more evenly through the pulse, and sharp edges from the tempering soften.
Salt continues to equalise across the dish, so the seasoning reads more integrated on the second day than on the first.
Reheating also drives another round of slow cooking, which continues to break down the pulses and deepen the body.
Why a dry sabzi goes the other way
A dry vegetable dish depends entirely on pieces staying distinct and on a certain amount of surface browning. Both are lost in storage.
Vegetables continue to release water in the container, which softens them and dilutes the seasoning that was clinging to their surfaces.
Reheating a soft, wet vegetable in a pan drives the water off but by then the vegetable has already gone past the texture it was cooked to.
What holds in between
Gravies with firm ingredients sit between the two. The sauce keeps well, and the solid pieces hold up for a day or two before softening noticeably.
Dishes built on chickpeas or kidney beans behave best in this group, since the pulses are already fully cooked and dense enough to resist further change.
Paneer and potato are the weakest members, both changing texture in the fridge in ways reheating does not undo.
How to plan a week around it
The workable pattern is to batch the wet dishes and cook the dry ones fresh, since a dry sabzi is usually the fastest thing in the repertoire anyway.
A dal, a bean gravy and a base paste made once cover most of a week's wet components, with fifteen minutes of fresh vegetable cooking alongside.
That split keeps the elements that reward keeping and cooks fresh only the ones that genuinely need it.