Step 1

In a large pot over medium, heat the oil until shimmering. Add the scallion whites and ginger; cook, stirring, until fragrant, about 30 seconds. Add the potatoes, corn, broth and coconut milk. Bring to a simmer over medium-high, then reduce to medium and simmer, uncovered and stirring occasionally, until the potatoes are tender, about 15 minutes.

Step 2

Off heat, stir in the fish sauce, lime juice and scallion greens. Serve with lime wedges.