Thonmai
Walk through a wet market in Kumbakonam at seven in the morning and you can almost read the region's cooking in the air - the toasty smell of gingelly oil warming for a kaara kuzhambu, the sweet crackle of mustard seeds hitting groundnut oil, the coconut sharpness drifting from a kitchen preparing avial. Oil is not an afterthought in Indian cooking. It carries the dish's character. Choosing which wood-pressed oil to keep on your shelf is really a question of which food you cook most often.
Why the oil matters more than you think
A cooking oil does three jobs at once - it conducts heat, it carries fat-soluble flavour and aroma, and it lends its own taste to the food. In wood-pressed (marachekku) oils, that third job is more pronounced because the oil is crushed slowly at low temperature and left unrefined. Nothing is stripped out. That means a good groundnut oil tastes distinctly of groundnut, and a wood-pressed sesame oil carries the roasted note of the seed. This is a strength when the oil suits the cuisine, and a distraction when it does not.
Sesame (gingelly) oil for Tamil and South Indian tempering
Wood-pressed sesame oil, or nallennai as it is called in Tamil homes, is the backbone of Tamil Nadu cooking. Its deep, faintly nutty warmth is exactly what a tamarind-based kuzhambu, a puli inji or a vengaya sambar wants. It also carries the pickle tradition of the region - a properly made avakkai or maavadu relies on gingelly oil both for taste and as a natural preservative.
Best for - tamarind gravies, spicy pickles, seasoning idli podi, and drizzling over hot rice.
Note - use it in dishes where you want its flavour to be felt, not hidden.
Groundnut oil for Maharashtra, Gujarat and everyday Andhra
Wood-pressed groundnut oil is the most versatile of the three. It has a clean, mildly sweet body and a higher smoke point that suits high-heat cooking. This is why it anchors much of western and central Indian food - the tadka in a Maharashtrian amti, the frying of Gujarati farsan, the everyday cooking oil across large parts of the Deccan.
Best for - deep frying, sabzis, snacks like murukku and chakli, and general stovetop cooking where you do not want the oil to dominate.
Note - if your household cooks a wide mix of dishes, this is usually the safest single bottle to keep.
Coconut oil for Kerala and coastal Karnataka
On the Malabar coast, coconut is not a garnish but a foundation. Wood-pressed coconut oil brings a rounded sweetness that belongs with fish curries thickened with coconut milk, with olan and thoran, and with the beef and chicken preparations of Kerala Christian kitchens. It is also the classic medium for the Konkan and coastal Karnataka table.
Best for - Kerala and coastal curries, stir-fried thoran-style vegetables, and Onam sadya dishes.
Note - it sets solid below about 24 degrees Celsius, which is normal and reverses with gentle warmth.
Matching oil to your own kitchen, not the map
These pairings describe traditions, not rules. A Chennai household happily fries in groundnut oil and tempers in sesame; a Bengaluru cook might keep all three. The honest way to decide is to think about what you actually cook in a week. If it leans towards South Indian gravies and pickles, sesame earns its place. If you fry and cook broadly, groundnut. If your food is coastal, coconut. Many families settle on two oils rather than one, and that is a perfectly sound approach.
If you want to work out how much of each your kitchen goes through in a month before committing, our oil consumption calculator can give you a realistic estimate based on household size.
One honest caveat
"Wood-pressed" describes a cold-crushing method using a wooden or stone mortar, and it points to how the oil is made rather than a graded quality certificate. It is a descriptive term about process, not a regulated health claim. What it reliably gives you is an unrefined oil that keeps the seed's natural flavour - which is exactly why the regional pairings above hold up. Choose the oil that suits the food on your table, and the cooking will tell you soon enough whether you got it right.