Preheat a grill to medium high. Combine the olive oil, oregano, red pepper flakes and a pinch of salt in a small bowl. Brush the cut sides of the baguette with some of the flavored oil. Grill cut-side down until toasted, about 4 minutes.
Rub the grilled sides of the baguette with the garlic. Top with the tomato slices, season with salt and cover with the provolone. Grill, covered, until the cheese melts, 3 to 5 minutes. Drizzle with the remaining flavored oil and season with salt. Cut into pieces.