Indian cuisine is regional and changes significantly as you travel north to south and east to west. The biggest distinction is north India's preference for bread, meat, and chai (tea), compared to the south's preference for rice, pulses, and coffee. But Mumbai is a mixture of cultures, as motley as the crunchy-smushy-salty-sweet-and-tangy tastes of a bhelpuri street snack, and the dishes served are just as varied.
You'll delight in spicy curries with rice or naan, sweet and juicy mangoes, flavorful chutneys, warming biryanis, milky chai, fresh and sour lime juice, and pomfret cooked to perfection. And though many Indians are Hindus and don't eat meat, there are lots of non-vegetarian options, with mutton and chicken being most popular. One thing is certain: whether it's northern or southern, spicy or mild, vegetarian or not, the food in Mumbai will never fail to excite your taste buds.
Just as exciting as Indian food is for your mouth, so can it be for your stomach. The generous amounts of chilies making your eyes water and stomach knot are one thing, but quite another is the issue of sanitation. Having "Delhi Belly," or more accurately for this guide - "Bombay Belly"- is a hallmark of tourism in India and that includes expats. Until your body adjusts to the new bacteria, you'll probably go through a few stomach bugs. You should definitely take precautions where and what you eat. Snub all shabby eateries; wash and peel all fruits and vegetables; and leave the street food until after your immune system has built up. Consuming thoroughly cooked foods served steaming hot is a good way to avoid illness.
While in India, you might as well do as Indians do and try eating with your hand. Indians don't use eating utensils- just their right hands for scooping up and eating food. You won't be forced to, of course, but it is interesting to try at least once. Make sure you only use your right hand for eating and handling food.
If the novelty of Indian meals wears off, take comfort in knowing you can also enjoy western fare such as pizza, pasta, pork chops, and sandwiches whenever you yearn for something familiar. There are restaurants specializing in western cuisine where you can tuck into a plate of risotto or fill up on a burger and fries. Western food in restaurants rarely tastes exactly like it does back home, but it comes close enough to satiate most cravings.
Shopping for food is fairly easy. You can shop at huge indoor supermarkets, smaller specialty stores, or outdoor markets. Fresh produce is very inexpensive as are most foodstuffs such as bread, eggs, milk, and bottled water. Prices at outdoor produce markets are usually negotiable. A foreign face automatically rises prices, so offer about half of what is quoted and negotiate from there. Even without bargaining, your bag of groceries will probably be much cheaper than at home.
There isn't an expat who doesn't desire snacks from home once in a while. For these cravings, there are several stores carrying international products imported from countries such as the UK, the States, Singapore, Germany, France, Belgium, and Holland. But your money will go quickly on imported goods and alcohol. If you eat mostly local items and reserve imported food only for occasional treats, you can manage spending very little on your groceries in Mumbai.