Heat the oven to 400°F and line a half-sheet pan with parchment paper.
Spread the tortilla chips across the pan in a single layer, slightly overlapping, edge to edge.
Sprinkle about half the grated cheese over the chips.
Scatter the black beans and corn over the cheese-covered chips.
Cover everything with the remaining shredded cheese so the pan looks loaded edge to edge.
Bake for 5 to 10 minutes, until the cheese is fully melted and bubbling and the chip edges look golden. Watch the last two minutes closely.
Scatter the diced tomato, red onion, jalapeño rings, and cilantro over the hot nachos by hand.
Drizzle the sour cream in thin zigzag lines over the top. Serve right away, on the pan, while the cheese is still molten.