Being involved in fitness and exercise activities for a considerable amount of time, I understand the need for 'perfect' abdomen or abs. Indian genetics are different from those of westerners so consuming proper Indian diet which suits our genetics and climate becomes absolutely must. In general, the following aspects can help you develop well defined abs:
1)If you are vegetarian, its advisable to eat more of legumes, pulses,lentils like moong,kidney beans,gram(chana) in form of dal or just cooked. Also, green leafy vegetables like spinach can be consumed.
2)If you are non-vegetarian, then eggs and other poultry products
like chicken breast(roasted or boiled but not fried) are your best bet.
3)The above diet is necessary for proteins which build your abs muscles, but along with them, your carbohydrates, minerals and vitamins need to be well balanced.
4)The key is not over-eating and bloating your stomach, that makes your tummy stick out. Have 6-8 meals in a day staring with a good breakfast. Drink lots of water throughout the day.
5)Apart from that, mix your weight training with cardio exercises like aerobic or running for about 3-4 days a week. Avoid junk food, fried food and oily items.This lets you shred the fats off your tummy and reveal those muscles beneath!
CAUTION: The abdomen is core part of body and over-exercising can cause injuries which can ruin body posture in old age. The above tips are general but I would still suggest consulting a dietitian for designing diet plan specific to your body type.