Onion Pastes Both fried onion paste and boiled onion paste help provide thickness to the gravies. They indeed help to add base or body to the dish apart from acting as colouring agents too
Nut Pastes Various types of nuts ground into a fine paste are used in thickening for Indian gravies. These are probably the influence of Mughal rulers and hence, mostly found in Mughlai kormas and curries often referred to as Indian royal cuisine. There are many of the nut pastes, such as cashew nut, almond, and coconut. Apart from these, sometimes for special gravies, pistachio paste can also be used in thickening of gravy.
Seed Pastes Many kinds of seeds are used in paste form to provide thickening to curries and dishes. For example, poppy seed paste, chironjee paste, char magaz paste. Many other seeds such as sesame seeds are used in paste that also acts as a thickening agent. Mustard seeds are also used in the form of paste that acts as thickening and flavouring agents in many Bengali dishes.
Masala Pastes Many types of dry masalas and wet masala pastes are used in the thickening of the dishes in Indian cuisine.
Lentils Many Indian preparations use lentils for thickening purposes. It is used in various forms around India
Dairy Products Many types of dairy products, such as cream, etc., are used in Indian cooking to thicken some gravies, especially in Mughlai cuisine. Such use of dairy products is more prevalent in hotels and restaurants, and is rarely done in home style food. This is probably the influence of Western cooking.
Vegetable Purees Certain vegetable pastes, such as fresh turmeric, ginger, and garlic pastes, are also used for thickening of curries. Some green leafy vegetable pastes, such as spinach, fenugreek, etc. are used in thickening curries and dishes