Caramelize onion by melting 3 tablespoons butter in a saute pan over medium heat. Add onion. Cook for 15to 20 minutes, or until onion is a deep brown, stirring occasionally. Remove from heat and reserve.

Sprinkle your rolling surface with a handful of cornmeal or flour. Place dough in the middle of the surface. Roll dough out gently 1/4-inch thick, into either a 12-inch rectangle or circle. Brush both sides with olive oil and set aside until ready to grill.

If you are grilling on a charcoal grill, set coals on one side of the grill.

Place dough directly on the cooking grate over medium heat for 1 to 3 minutes, until the crust is well marked and browned. Flip dough and spread tomato slices evenly over crust. Sprinkle onion over top, then sprinkle cheese over the top. Move to indirect heat (for charcoal: the side of charcoal grill that has no coals. For gas: turn off burner directly under pizza). Cover grill and cook for 5 to 10 minutes, or until bottom is well browned, and cheese is fully melted.

Remove from grill, season with salt and pepper and slice. Serve immediately