Black Rice Salad with Mango and Peanuts

INGREDIENTS

• 2 oranges
• 1/4 cup (or more) fresh lime juice
• 2 tablespoons vegetable oil
• 1 tablespoon fish sauce (such as nam pla or nuoc nam; optional)
• 2 cups black rice (preferably Lotus Foods Forbidden Rice)
• Kosher salt
• 2 just-ripe mangoes, peeled, pitted, cut into 1/2" dice
• 1 cup fresh cilantro leaves
• 1 cup finely chopped red onion (about 1/2 large onion)
• 1/2 cup unsalted, dry-roasted peanuts
• 6 scallions, thinly sliced
• 2 jalapeños, seeded, minced