To roast the tomatoes— Heat the oven to 350°F. Coat the tomato halves with the olive oil, season them lightly with salt and pepper, and arrange them, cut side down, on a parchment-lined rimmed baking sheet. Roast for about 2-1/2 hours. The tomatoes should be very concentrated and browned, and most of their juices will have cooked off. (The tomatoes can be cooked a day or two ahead and refrigerated; before serving, bring to room temperature.)
To make the salad— In a bowl, combine the bulgur, boiling stock, and half the olive oil; cover and let stand for at least 30 minutes. Uncover and fluff with a fork. Stir in the remaining olive oil, the parsley, mint, scallion, garlic, lemon juice, and zest. Taste and add salt and pepper as needed.
To serve— Mound the tabbouleh in the middle of each plate and arrange the roasted tomatoes around the tabbouleh. Garnish with the pine nuts and sprigs of mint.