Preheat the oven to 450°F.

Place the potatoes in a large pot and add enough water to cover. Stir in the salt and bring to a boil over high heat, then reduce to a simmer. Cook until fork-tender, about 8 to 10 minutes—they should be tender but still firm enough to hold their shape.

Drain the potatoes thoroughly in a colander. Transfer them to a large baking sheet and toss with olive oil until well coated, then spread them out in a single layer ensuring the pieces do not touch so they crisp properly.

Roast the potatoes for 40 minutes, flipping halfway through, until the edges are deeply browned and the skins are crisp. Remove from the oven and immediately sprinkle with garam masala and extra salt to taste, tossing while the potatoes are hot to help the spices stick.

Arrange the hot potatoes on a large serving plate. Layer the yogurt and chutneys over the top, then finish with the sev, chat masala, herbs, and any desired fresh vegetable toppings. Serve immediately while the potatoes are still crackling.