Every region of India has its favorite oils, many of which not only provide fat for searing and sizzling but also infuse flavor. Ghee (clarified butter) is often uses, as it is great for deep-frying because it has high smoke point. Flavorless oils with a high smoke point (the temperature at which oil starts to smoke) are essential for sizzling whole spices and searing meat, fish, and poultry before we stew them in sauce.
Vegetable-based oils, including canola (which is not rapeseed oil), work perfectly for this. Peanut and corn oil also work well for this purpose, but many people are allergic to peanuts. Rice oil found it to be part of "flavorless" category and since it is rich in antioxidants, contains no trans fat, and has a smoke point at 490° F, also it is good for Indian cooking.
In the Southwest India and Sri Lanka very popular is coconut oil, rich with buttery taste and saturated fats. The lauric acid in coconut oil helps to fight infections (this is the same acid found in mothers' breast milk). The Southeast prefers unrefined sesame oil for its delicate nutty taste. Mustard oil, much valued in Northeast, North and Northwest is known for bitter taste in the curries.
To add flavor to cooking, spices can be added to the oil. Once we perfume the oil with spices it is hard not to notice the role of garlic and onion in providing the subsequent layer of sauce. Raw or pureed onions taste pungent, but when stir-fried long enough so that the starches change to sugars, their sweet personality takes over, giving a curry incredible sweetness.
This is an orange-colored oil popular in Chinese cooking, use it in very small quantities to dribble into soups and sauces.
Heated vinegar mixed with fresh spices will assume their flavors, and can be used to create wonderful salad dressings.
The best vinegar to use is a white vinegar, but apple cider, white wine, and rice vinegar all work well. You can use these vinegars alone or in combination.