The best ones to use are ripe tomatoes that are in season. As far as type, plum tomatoes or Roma tomatoes are great, but I've also made this recipe with cherry tomatoes and grape tomatoes. But, feel free to use garden summer tomatoes or heirloom tomatoes if you find different varieties at a farmer's market or if you grow them yourself. If tomatoes are out of season, you can make this recipe with high-quality canned tomatoes. I like canned San Marzano tomatoes.