Who says tomatoes can't be the star of the show? Grill a thick, juicy slice of beefsteak tomato and get all the meatiness you want from a burger without the beef.
Drizzle tomato slices with oil and season with salt and pepper. Grill over medium-high heat, turning, until juicy and charred in spots, about 5 minutes.
Top bun bottoms with cheese and grill, covered, until just melted, about 1 minute. Top with grilled tomatoes and garnish with basil.