INGREDIENTS
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1/4 cup smooth Dijon mustard
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1/4 cup grainy mustard
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1 (14 to 16-pound, 7-bone) whole prime rib roast
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1 tablespoon whole white peppercorns
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1 tablespoon whole black peppercorns
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1 tablespoon whole green peppercorns
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1 tablespoon whole Sichuan peppercorns
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Kosher salt
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1 1/2 cups all-purpose flour
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3/4 teaspoon kosher salt
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3 eggs, preferably at room temperature
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3/4 cup warm water
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3/4 cup warm milk
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1/2 cup unsalted butter, melted, plus a little extra for greasing the baking dish
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Special equipment: 1 (9-inch) round baking dish