The tomato matters. We made these while waiting for the grill to cool; we started the tomatoes in a quick foil boat over the super high heat.

• Cut the top and bottom off of a few tomatoes- you want a flat bottom for the grill, and a flat top for the cheese;
• Drip a little Worcestershire sauce in each tomato- very little;
• Layer thin slices of aged cheese- any; we used Toma from a Bay Area maker: Point Reyes (worth every penny);
• Put over hot coals. We started them in a simple foil boat, and left them in it until the tomatoes were bubbling hot, we then transferred them to the (very) hot grill, and closed the grill lid; within a few minutes, they were sizzling with browning cheese on top. Fantastic.
• we let them cool, and ate them in little sandwiches of sourdough baguette. Fantastic.