I don’t know about the average Indian’s cuisine, but we have access to many extant culinary manuscripts that were being used at the courts of Persianate Muslim rulers in the subcontinent, starting from the Ni’matnama (“Book of Pleasures” in Persian) of the 15th century, to Nushka-i-Shahjahani and Khulasat-i Makhlut u Mashrubat, both manuscripts from the Mughal period.

This elite Indo-Persian cuisine was a hybridized blend of Central Asian, Turkic, Iranian and Indian cuisines, and has often been compared to contemporary Safavid Iranian cuisine. However, unlike with the Iranians, there is a trend in Indo-Persian cuisine of progressively incorporating more native Indian dishes into the menu.

For example, the Ni’matnama (sponsored by Sultan Ghiyas Shah of Malwa) features many meat-heavy dishes familiar across Iran, Central Asia and northern India — sambosas, pilaf, kebabs, biryani, etc.

But the recipes are heavier on traditional Southeast Asian spices that had long been familiar to the Middle East and India: saffron, camphor, cardamoms, cloves, coriander, cinnamon, cumin, musk, ambergris, turmeric, black pepper, raisins, tamarind, pistachios, pine seeds, etc., meaning native Indian dishes in that area of the subcontinent (south India) were extensively using “Old World” spices even before the arrival of the chilli pepper, as were Middle Easterners and Central Asians.

Although the Ni’matnama and Nushka-i-Shahjahani (“Delights of Shahjahan” in Persian) are more focused on meat-based Iranian dishes, they do list some staples from western and southern India — one was a yogurt broth made with chickpea flour, and another was swollen grain. It seems Indians generally practiced fermentation in food-processing a lot — many of the native Indian dishes mentioned are made by fermenting either dairy (yogurt, paneer) or grains.

This thread covers this topic and is pretty detailed. https://old.reddit.com/r/AskHistorians/comments/4rwri1/what_was_indian_food_like_before_contact_with_the/