In a medium saucepot, bring broth and Worcestershire sauce to a boil.

Reduce heat to medium, add tempeh and simmer 20 minutes or until tender.

Preheat the oven to 400°F.

Transfer simmered tempeh to a baking dish and bake until heated through, about 15 minutes.

Meanwhile, in a small bowl, stir together yogurt, relish and ketchup until blended.

Evenly divide dressing, spreading on each slice of bread, then arrange tempeh on 4 slices of bread.

Spread sauerkraut evenly over tempeh, then top with cheese and remaining bread slices, dressing-side down.

Heat a large skillet over medium heat.

Spray lightly with oil, then arrange sandwiches in the skillet in a single layer (you might have to work in batches).

Arrange a large heat-proof plate on top of the sandwiches and weigh it down with a can or heavy saucepot to firmly press the sandwiches.

Reduce heat and cook until golden brown, 3 to 4 minutes.

Flip sandwiches over and continue to cook until heated through and golden brown on both sides.

Cut sandwiches in half and serve immediately.