You’d think I didn’t like fresh tomatoes, the way I avoid them most of the year. Yet it’s precisely because I love tomatoes — ripe, juicy, just-plucked and not shipped-around-the-world ones — that I wait until summer. At last the season has arrived, filling my dinner plate with colorful rounds of heirloom tomatoes. Here’s one way I like to serve them: a simple salad with a sweet, tangy pomegranate and sumac dressing and a handful of fresh herbs.