South India's  four states' has rice as a staple food, the use of lentils and spices, use of dried red chilies and fresh green chilies, coconut and native fruits and vegetables like tamarind, plantain, snake gourd, garlic, ginger, etc.

overall all the four south Indian foods have much in common and differ mostly in the spiciness or hotness of the food.

Andhra Food

Described as the spiciest of these four states' cuisines, there is a generous use of chilli powder oil and tamarind. The most famous food items are:

Vegetarian: pesarattu, pulihora (or pulihaara), Gongura, avakkai (cut raw mango) pickle.

Non-vegetarian: Kodi iguru( chicken stew), Kodi pulusu(chicken gravy), Chepa pulusu (fish stew) etc., Hyderabadi Biryani

South Indian Cuisine a great variety of dishes, with the majority being vegetable or lentil based..

Karnataka Food

Described as the mildest (in terms of spice content) of the South Indian Foods , there is a generous use of palm sugar or Jaggery and sparingly used chilli powder. Since the percentage of vegetarians in Karnataka is higher than other southern states, vegetarian food enjoys widespread popularity. Udupi cuisine forms an integral part of Karnataka cuisine. Also, Karnataka cuisine is very diverse. Broadly, North Karnataka, South Karnataka also known as Bayaluseeme or the Old Mysore region, Coastal or the Canara cuisine, Coorgi Cuisine.

South Indian Breakfast dishes include Masala Dosa, Ragi rotti, Akki rotti,Vangi Bath, Khara Bath, Kesari Bath, Davanagere Benne Dosa,Uppittu,Plain and Rave Idli, Mysore Masala Dosa, Kadubu, Poori etc.

Kerala Food

Kerala cuisine is quite diverse. The diversity is best classified on the basis of the various communities. The Hindus, especially the Namboodris and Nairs have a predominantly vegetarian cuisine, whilst the Christian and the Muslim communities have a largely non-vegetarian cuisine. OF that syrian christian dishes and malabari muslim dishes are famous.Since Kerala's main export is coconuts, almost all of the dishes, irrespective of the variety in the cuisines of the different communities, have coconuts associated with them, either in the form of shavings or oil extracted from the nut. Seafood is also very popular in the coastal regions and eaten almost every day.

Vegetarian: olan, paalpradaman, nendarangai chips, aviyal,pulissery, erucherri, sambar, rasam, kalan,upperis,pachady, kichadi,

Non-vegetarian: shrimp coconut curry, fish curry (various versions depending on the region), fish fry, kerala beef fry, chicken fry with shredded coconuts,beef ularthyathu,fish pickle, pork masala, podimeen fry, meen thoran(fish with coconut),Karimeen(pearl spot fish)pollichathu,shrimp masala,chicken stew, mutton stew,duck curry, malabari fish curry, kakka(shells)thoran, kalllumekka, crabs, malabar biriyani, thalassery biriyani,pearl spot fish, jewel fishes, mussels, squid, kappa boiled, kappa(tapioca)vevichathu with non vegiterian curries, etc Snacks:upperi,payasam, banan fry (ethaykkappam or pazham pori),ullivada,kozhukkatta,avalosunda,unniyappam,neeyyappam,unnaykka,thira,churuttu,boli,modhaka

Tamil Food

Tamil cuisine groups dishes under four slightly overlapping categories. First are the dishes that necessarily are mixed with rice; various Kuzhambu, Sambhar, Paruppu, Rasam, Thayir, Kadaiyals and the likes belong to this category. The second are the side dishes that accompany such mixture; Kootu, Kari, Poriyal, Pickles, Papads fall into this category. Third are the short snacks and their accompaniants; vadai, chips, bonda, bajji, soups, various chutneys, thayir pachadi and the likes belong to this category. Fourh

Vegetarian: idli, sambar, vadai, rasam,dosa, thayir sadam (yogurt rice), thayir vadai (yogurt-soaked fritters), kootu/kari (vegetables in wet style), poriyal (vegetables in dry style), murukku, uthappam, idiappam, appalam (deep fried lentil-flour crisps) and papadum (baked lentil-flour crips), freshly made thayir pachidi (yogurt mixed with fresh vegetables).

Non-vegetarian: karuvattu kuzhambu (salted, dried fish in wet sauce), chettinad pepper chicken, Fish Fry

South Indian Recipes are rice based such as dosais, appams, idiyappams, adais and idlis. The Chettinad people through their mercantile contacts with Burma, learnt to prepare a type of rice pudding made with sticky red rice.

Chettinad cuisine offers a variety of vegetarian and non-vegetarian dishes. Some of the popular vegetarian dishes include idiyappam, paniyaram, vellai paniyaram, karuppatti paniyaram, paal paniyaram, kuzhi paniyaram, kozhakattai, masala paniyaram, adikoozh, kandharappam, seeyam, masala seeyam, kavuni arisi and athirasam. Source -wikipedia