Almost as elemental as fire is the warming soup we make from it. A big pot, a few gnarled vegetables, a rind of cheese, a crust of bread. From these humble ingredients we can coax something truly sublime and nourishing. The tender green vegetables of spring soften with just a kiss of heat, but winter's sturdy bounty must be stewed into submission. A heap of sliced onions—that mainstay of the cold-weather kitchen—collapses, then caramelizes, turning the rich, burnished brown of aged leather. Once crisp and biting, they develop a sweet and savory intensity that gives a plain broth spectacular depth. The ultimate peasant food, French onion soup is topped with well-toasted slices of rustic bread beneath a bubbling blanket of melted cheese. Time and tender care are all you need to make this simple yet soul-satisfying dish.