This is Michael Psilakis's modern take on the traditional Greek combination of watermelon and feta cheese. It features the creamy yogurt he grew up eating in New York's Long Island: "My mom made it at home all the time, and we'd snack on it with honey after school." Michael Psilakis: Defining Greek Food More Greek Recipes
Light a grill. In a bowl, combine the yogurt with the lemon juice, vinegar, thyme and the 1 tablespoon of olive oil. Season with salt and pepper.
Drizzle the watermelon triangles with olive oil and season with salt and pepper. Grill over high heat until nicely charred, about 1 minute per side; transfer to plates. Top the watermelon with the yogurt sauce and season with black pepper. Drizzle with olive oil, garnish with the mint and serve.
The yogurt sauce can be refrigerated overnight. Bring to room temperature before serving.