In a small bowl combine the rub ingredients. Set aside 1 teaspoon of the rub for the chutney and use the rest to season the roast evenly on all sides. Loosely wrap the roast and refrigerate for at least 1 hour or overnight.
Allow the pork to stand at room temperature for 30 minutes before grilling. Soak the wood chips in water for at least 30 minutes.
Prepare the grill for direct and indirect cooking over low heat (250° to 350°F).
Brush the cooking grates clean. Drain and add the wood chips to the charcoal or to a smoker box of a gas grill, following manufacturer’s instructions, and close the lid. When the wood begins to smoke, cook the tomatoes over direct low heat, with the lid closed, until very soft, 25 to 30 minutes, turning occasionally. Remove from the grill and let cool. Cook the roast over indirect low heat, with the lid closed, until an instant-read thermometer inserted into the thickest part of the roast registers 185°F, about 3-¾ hours. The meat should be tender but not falling apart. Remove from the grill, tent with foil, and let rest for while you make the chutney.
Peel, core, and roughly chop the tomatoes. In a medium saucepan over medium-low heat, warm the vegetable oil. Add the onion, cumin seed, coriander, cayenne, and the reserved 1 teaspoon rub and cook until the onion is tender, about 8 minutes, stirring frequently. Add the tomatoes, vinegar, sugar, and raisins and bring to a simmer. Cook, uncovered, at a gentle but steady simmer until thickened, about 25 minutes, stirring occasionally. Season with the salt and pepper. Let cool to room temperature.
Lightly brush the naan on both sides with olive oil, and then grill over direct low heat until warm, about 2 minutes, turning once or twice. Cut the roast crosswise into ½-inch-thick slices. Serve warm with the naan and the tomato chutney.