Cooking in foil packets makes for a tidy grill, and allows all the flavors to mingle and intensify. Here, thick slices of potato and onion are seasoned and cooked with butter until tender and brimming with flavor.

Cooking in foil packets makes for a tidy grill, and allows all the flavors to mingle and intensify. Here, thick slices of potato and onion are seasoned and cooked with butter until tender and brimming with flavor.