Halloumi, a salty, almost meaty Greek sheep's-milk cheese, is remarkable not only for its rich flavor but for its ability to stand up to frying and even grilling while holding its shape (it's a popular addition to kebabs). In this dish, pan-seared slabs of cheese pair with tomatoes to make a deliciously simple summer salad. For an even heartier main course, add grilled chicken or shrimp. Note: Halloumi is increasingly available in the cheese department of many supermarkets (usually under the Mt. Vikos brand). You may also find it at any Whole Foods market or cheese shop.
In a small bowl, whisk together shallot, vinegar, and salt. Add ½ cup olive oil in a slow stream, whisking until emulsified, and set aside.
Cut tomatoes crosswise into ½-inch-thick slices and arrange on a platter or on four small plates. Cut halloumi into ¼-inch-thick slices. Heat remaining 2 teaspoons olive oil in a medium-size nonstick frying pan over medium-high heat, and fry halloumi slices until golden brown, about 2 minutes per side. Arrange cheese over tomatoes, and drizzle shallot vinaigrette on top. Tear basil leaves over top. Sprinkle with pepper, if you like. Serve immediately.