There are several restaurant options available in Leh. Depending on the kind of food you want to eat. The authentic cuisine includes Chhurpi (Cheese made out of Yak Milk), Gur Gur Chai (Butter Tea), Mokhtuk, Thukpa, Tingmo, etc.
If we were to recommend, we'd recommend the combo of Tea and Maggi at the world's highest Maggi Point en-route Khardung La Pass.
If you want to have a taste of the best Tibetan food, then you can go to The Tibetan Kitchen.
Restaurants like Lamayuru, Andrew, Bon Appetit serve north Indian food for those who don't want to experiment and have the taste of food that reminds them of home.
There are lots of cafe's that you can explore in Leh Market.
However, make sure to carry dry snacks when traveling to Nubra and further because you won't find many outlets there.