Cut baguette into 1/2-inch slices.
Place baguette slices on a cookie sheet and broil in the oven until the top is browned. Alternately, place baguette slices directly on a charcoal or gas grill grate and grill until the top is browned.
Flip baguette slices over and brush with olive oil. Toast under broiler or on grill grate until browned.
Remove baguette slices from the oven/grill.
While still hot, rub the cut side of the garlic on one side of the toasted baguette slices, allowing the rough crumbs to scour the surface.
Rub the cut sides of the tomato quarter over one side of the toasted baguette slices so that some of the flesh gets scraped onto the surface of the bread.
Sprinkle with salt, if desired, and serve immediately.