Tandoori aloo (tandoori potato) turns up at grill parlors throughout northern India. The recipe may look complicated, but actually it’s a series of simple steps.
Step 1: Precook the potatoes (this can be done up to 24 hours ahead).
If you are grilling the potatoes, use the indirect method: Set up the grill for indirect grilling, place a drip pan in the center, and preheat the grill to medium-high. When ready to cook, prick the potatoes with a fork in a few spots, brush them with oil, and season them with salt and pepper. Place the potatoes in the center of the grill over the drip pan and away from the heat and cover the grill. Grill the potatoes until you are just able to pierce them with a slender skewer, about 40 minutes.
If you are parboiling the potatoes, place them in a large pot, add cold salted water to cover by 4 inches, and bring to a boil over high heat. Boil the potatoes until barely tender, about 30 minutes. Use a bamboo skewer or fork to test for doneness; you should be just able to pierce them. Drain the potatoes well in a colander, rinsing them under cold running water until cool.
Step 2: Cut each potato in half crosswise. Cut a very thin slice off the bottom of each half potato so you can stand it upright. Using a melon baller or spoon, hollow out each potato half to within 1/4 inch of the side, transferring the potato to a mixing bowl. Finely chop or mash the potato. Reserve the potato shells.
Step 3: Add the cilantro, scallion, chile pepper, sesame seeds, paneer, and butter to the chopped potato and stir to mix. Season with salt and black pepper to taste; the filling should be highly seasoned. Stuff the filling into the hollowed-out potato halves. The potatoes can be prepared up to 6 hours ahead to this stage and refrigerated.
Step 4: Make the yogurt spice paste; Place the garlic, ginger, paprika, 1 teaspoon of salt, and the coriander and cumin in a food processor and finely chop them. Add the yogurt, oil, and lemon juice and puree to a smooth paste, scraping down the side of the processor bowl with a rubber spatula. Taste for seasoning, adding the black pepper and more salt as necessary. Transfer the spice paste to a shallow bowl. Place 1/4 cup of the sesame seeds in a shallow bowl and the remaining 1/4 in a measuring cup.
Step 5: Set up the grill for indirect grilling and preheat it to high.
Step 6: When ready to cook, brush and oil the grill grate. Spoon half of the yogurt spice paste over the potato halves, then sprinkle the paste with the sesame seeds in the measuring cup. Dip the bottom of each potato half in the remaining yogurt spice paste, then in the remaining sesame seeds. Arrange the potatoes upright on the grill over the drip pan and away from the heat. Grill the potatoes until they are golden brown on the outside and bubbling in the center, 15 to 25 minutes. Transfer the potatoes to a platter or plates and serve at once.