Indian cuisine, be it Punjabi, Bengali, Maharashtrian, South Indian or whatever; is distinctive  mainly for its different varieties of curries.
These varieties vary from region to region, dependent mainly on the availability of the types of ingredients in that region. The base for most curries, bet it vegetarian or non-vegetarian dishes, is the gravy. A gravy is generally made up of a variety of spices and other ingredients, each combination resulting in a distinctive taste and flavour.

Expensive ingredients and lack of time, especially for working women, make it a near-impossible task to prepare the elaborate curries with gravy on a daily basis. However, it is possible to prepare some very easy-to-prepare gravies beforehand and store in the refrigerator for future use. The ingredients used are easily available in the kitchen and are quite economical too.
Making the gravies in a large batches and storing in the refrigerator will enable you to make different curries for at least 10-15 days without elaborate preparation each time.

Some easy-to-make gravies can be made in the following manner:

1. Blanch and puree about a kilogram of tomatoes and store in an airtight container in the refrigerator. Make sure the tomatoes are fully ripe. When this ouree is added to a dish with other spices, this not only gives good taste but also a great color too.

2. Onions are a very good material for rich gravies. Make thick slices of onions, fry them in little oil and make a smooth paste and store in the refrigerator. Alternatively, whole peeled onions burnt black over direct fire when ground to smooth paste with roasted dry coconut and about a spoon of roasted cumin seeds is another way to make a great gravy. In Maharashtra, this type of gravy is usually made with lentils and sprouts etc. A little bit of tamarind too can be added while grinding this paste. Finely sliced onions, fried crisp in oil and powdered are excellent for egg, meat and chicken dishes.

3.  Tamarind pulp is a also a good thickening agent. Making tamarind pulp in large batches will save on time required to prepare the pulp each time which involves soaking the tamarind and extracting the pulp. Another way of using tamarind is to clean it thoroughly, wash and dry in the sun until it is crisp dry. Make a fine powder of it in the mixer and store in an airtight jar. This works equally well as fresh pulp.      While adding the tamarind pulp to any gravy, add it towards the end of the cooking process or until all the vegetables are cooked.

4. Refined flour or maida is another good ingredient to prepare a gravy or can be used in any soup preparation. Roast the maida in a little bit of butter for few minutes. Ensure that it does not change color. Let it cool for some time, then prepare a paste of this in either milk or water or vegetable stock if available. The paste should be thin in consistency because it will become thick when cooked. Cook this paste on fire for a few minutes until it changes color and becomes transparent, stirring constanatly so that no lumps are formed. Add salt and pepper powder to this, cool and store. You can lttle sugar to it too, especially if using in soups. While adding this white sauce to any dish, add only one or two spoons and not more. This white sauce is especially useful when preparing kurma dishes.

5. Bengal gram flour or besan can also be used to thicken gravies. A spoonful of besan, slightly roasted and added to the curry thickens it well with a distinctive flavor. Especially works well with mixed vegetables.

6. Curds are another good option. Curds are used extensively in many Moghlai and Kashmiri dishes. Before adding curds, make sure tehy are beat to a smooth consistency to give a good texture and taste. Curds also work as a tenderiser for meats.

7. Coconut milk is another good option for preparing gravies. Though it will not thicken the gravy much, it gives a great taste and flavour. When using coconut milk, add salt towards the end of the cooking or else the milk will curdle.

8. Four to five big onions, thickly sliced, red chillies as per taste, 2 tablespoons of chana dal, all fried in oil separately and ground to a smooth paste with a few cloves of garlic makes a good gravy . Adding dry roasted coconut and tamarind while grinding will also impart it a distintive flavour.

9. A smooth mixture of groundnuts,  sesame seeds, dry grated coconut, all roasted seperately and then ground together with a pinch of salt makes good gravy for vegetables such as cauliflower, potatoes and peas etc.

10. Fresh coconut, fresh green coriander leaves, some minty leaves, green chillies and a little bit of ginger, make a smooth paste and store in the refrigerator. This works well for single or mixed vegetables and also while preparing sprouts , lentils etc.

11. In Bengali cuisine, a smooth paste of khuskhus (poppy seeds) soaked for some time in water, with mustard seeds and green chillies is used in many dishes. The mustard seeds gives a quite sharp but distinctive flavour to the dish.