From Cook's Illustrated, linked from their Sous Vide Pork Tenderloin recipe. They really recommend white pepper.
Ingredients
6 scallions, white and green parts separated and sliced thin
2 teaspoons grated fresh ginger
1/2 teaspoon ground white pepper
1/2 teaspoon grated lime zest plus 2 teaspoons juice
1/4 cup vegetable oil
2 teaspoons soy sauce
Instructions
Combine scallion whites, ginger, pepper, and lime zest in heatproof bowl. Heat oil in small saucepan over medium heat until shimmering. Pour oil over scallion mixture. (Mixture will bubble.) Stir until well combined. Let cool completely, about 15 minutes. Stir in scallion greens, lime juice, and soy sauce. Let mixture sit for 15 minutes to allow flavors to meld.