The main ingredient in a sushi roll is sushi rice, known as "shari" in Japanese. This type of rice is a short-grain variety that becomes sticky when cooked, allowing it to hold its shape when rolled with other ingredients. Sushi rolls often include various fillings such as fish, vegetables, and avocado, wrapped in seaweed (nori). The preparation of sushi rice involves rinsing, cooking, and seasoning it with vinegar, sugar, and salt, which enhances the flavor and texture. Sushi rolls can be both simple and complex, showcasing culinary creativity while providing a delicious and nutritious meal.