An Indian curry moved into a slow cooker often disappoints even when the recipe is followed exactly. The appliance does one thing well and two things the dish depends on badly.
The lid keeps water that should have left
A sealed slow cooker returns almost all its condensation to the pot, so nothing reduces. An Indian gravy is normally concentrated by evaporation over an open pan.
Vegetables and meat also release their own liquid into that closed environment, so a dish frequently ends up thinner at the finish than it was at the start.
The usual fix is to hold back most of the added water and to finish uncovered, either in the cooker on its highest setting or transferred to a pan.
Nothing browns at slow-cooker temperatures
Browning reactions need a dry surface and heat well above the boiling point of water, and a slow cooker never reaches either condition.
That matters more in Indian cooking than in a stew, because the base of most gravies is built from onions cooked until they color and sweeten.
Spices also need hot fat to release their oils, and a spice powder stirred into warm liquid tastes raw and dusty however long it is left there.
The base has to be built on the stove first
The practical arrangement is to fry the aromatics and spices in a skillet, then transfer that base to the cooker with the main ingredients.
This preserves the sequence the cuisine is built on while still using the appliance for the long, unattended part where tough ingredients soften.
Cooks who prepare bases in advance find this fits neatly, since a frozen portion of fried base can go into the cooker in the morning without a pan.
What the appliance is genuinely good at
Whole pulses and tough cuts benefit from hours at a gentle, stable temperature, which softens connective tissue and collapses beans without the constant attention a stovetop pot needs.
Dishes that are meant to be soupy rather than thick lose the least in translation, since the reduction problem does not arise.
It also holds food safely at serving temperature for hours, which suits a household eating at different times, provided the food reached that temperature by cooking rather than by warming slowly.
Multicookers change the calculation
An electric pressure cooker with a sauté function solves the sequence problem, allowing the frying, the pressure stage and an uncovered reduction in one insert.
Pressure cooking also reaches temperatures above boiling, which softens pulses far faster and produces a texture closer to what the recipes assume.
The tradeoff is attention, since a pressure cycle needs a cook present at the start and the end rather than a pot left alone through a working day.