The local "Brochettes" goat kebabs are delicious and are available in most bars and restaurants. Many restaurants also serve grilled fish and chicken, and frites and frites-banane fried plantain are ubiquitous.
In urban areas a local buffet known as "Melange" is sold at lunchtime. This consists of a buffet of mostly carbohydrates such as potatoes, bananas, beans, rice, cassava accompanied with some vegetables and a small amount of meat or fish with sauce. Note that Rwandan buffets are not all you can eat! You may fill your plate only once, and with practice you'll be able to stack your plate high like the locals do. Prices range from just over a USD$1 to USD$5 or even USD$10 depending on the grade of the eatery and the variety of food available. Most of the upper segment buffets $3 and above offer a salad buffet too. Note that many of the cheaper Melange places are unmarked.
Kigali has a much better range of restaurants than the rest of the country. Here you can find several Indian and Chinese restaurants, as well as Italian, Greek, French and multi-cuisine establishments charging around $10 for dinner.