Gratin Dauphinois Revived

March 21, 2011

Winter is on my head, but eternal spring is in my heart.
~Victor Hugo

They say spring sprang yesterday.

Equinox is derived from the Latin aequus (equal) and nox (night). The vernal equinox officially occurs when the center of the sun crosses the equator. But, be not dissuaded by the tale that on the vernal equinox the length of day is exactly equal to the length of night. Daytime to nighttime equality actually falls before the vernal equinox and likewise after the autumnal equinox.

For most venues on earth, there are two distinct days per year when the length of day and night are closest to being equal; those days are referred to as equiluxes, not to be confused with equinoxes. In a nutshell, equinoxes are points in time, but equiluxes are full days. An equinox happens each year at two precise moments in time—rather than two whole days—when there is a location on the earth’s equator and the center of the sun is observed vertically overhead.

To complicate matters, the earth’s atmosphere bends sunlight when approaching the horizon, so the sun appears to be above the horizon a few minutes earlier than actuality. Therefore, on the vernal equinox, the daylight hours are actually longer than the length of time between when the sun crosses the horizon at dawn and when the sun crosses the horizon at sunset. Those factors all combine to make the day of the equinox not the day when we have twelve hours each of light and darkness.

The vernal equinox also brings spring leeks to mind. Always, maybe too often, thinking food. Those sweet, green and white alliums that are planted in the fall and left in the frigid soil until the first thaw. Because farmers usually mound soil and mulch over leeks to protect them against cold temperatures, they tend to be grittier than their summer cousins. So, take care to clean them assiduously. Trim the roots, peel away the translucent outer layers and slice the leeks in half lengthwise. Wash well under cold running water.

GRATIN DAUPHINOIS WITH MUSHROOMS & LEEKS

1 plump, fresh garlic clove, peeled and lightly crushed
Butter, unsalted

2 large leeks, cut lengthwise, cleaned thoroughly, then sliced thinly crosswise
8 oz crimini mushrooms, thinly sliced
4 T unsalted butter, divided
2 t dried thyme
Sea salt and freshly ground black pepper
2 lbs baking potatoes, preferably russets, peeled and very thinly sliced

2+ C grated gruyère cheese
1+ C heavy cream

Sea salt and freshly ground black pepper
Freshly grated nutmeg

Preheat the oven to 375 F

Melt butter 2 tablespoons butter in a large skillet over medium high heat. Add sliced leeks, thyme, salt and pepper. Sauté, stirring occasionally, until leeks are tender and golden, about 5-7 minutes. Set leeks aside in a bowl. Wipe skillet with a paper towel.

Melt an additional 2 tablespoons butter in the same skillet over medium high heat. Add sliced mushrooms, salt and pepper. Sauté, stirring occasionally, until mushrooms are tender, about 8 minutes. Set mushrooms aside in a bowl.

Thoroughly rub a shallow gratin/baking dish with a crushed garlic clove, and then lightly butter the dish with the end of a stick of butter. Arrange one half of the sliced potatoes slightly overlapped in a single layer. Strew cooked leeks and mushrooms over the potatoes. Sprinkle with half of the cheese and then half of the cream. Season with salt and pepper. Add a second layer of potatoes with cheese, cream and season again with salt and pepper. Lightly grate some fresh nutmeg on the top layer to finish.

Place the baking dish in the center of the oven and bake until crisp and golden, about 1 hour. Should the top begin to brown too rapidly, simply cover with aluminum foil. Remove from oven, let rest for at least 10 minutes, and then serve.

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