Queso Fundido

extra-virgin olive oil

large poblano chile, seeded and cut lengthwise in quarters, then crosswise in 1/4-inch strips (1 cup)

onion, thinly sliced (1 1/4 cups)

Kosher salt

serrano chile, thinly sliced, seeded if desired (1 tablespoon)

low-moisture mozzarella (such as Polly-O), cut into 1/2-inch cubes

fresh goat cheese, crumbled

Jicama sticks, radishes, and tortilla chips, for serving