Miso-Marinated Flank Steak

INGREDIENTS

• 1/4 white miso (fermented soybean paste)
• 2 Dijon mustard
• 1 grated peeled ginger
• 1 kosher salt
• 1 garlic clove, grated
• 2 vegetable oil plus more for brushing
• 1 1/2 grass-fed beef flank steak
• Flaky sea salt, such as Maldon, and freshly ground black pepper
• White miso, also known as shiro miso, is available at Japanese markets, natural foods stores, and in the refrigerated Asian foods section of some supermarkets.