In a saucepan, combine the tomato sauce, olives, capers, raisins, vinegar, and Monk Fruit In The Raw®. Pour in 1/4 cup water. Bring to a boil over medium-high heat, then reduce the heat and simmer the mixture gently, uncovered, for 5 minutes. Set the mixture aside.
Heat 2 tablespoons of the oil in a large skillet over medium-high heat. Add half the eggplant and cook, stirring occasionally, until the cubes are lightly browned, about 6 minutes. Transfer the eggplant to a plate. Add 2 more tablespoons oil and brown the remaining eggplant, about 5 minutes. Add it to the already cooked eggplant.
Heat the remaining oil in the pan. Add the celery and onions, and cook until the onions are golden, 6-7 minutes, stirring often. Return the eggplant to the pan. Add the hot tomato sauce mixture. Simmer the caponata, uncovered, until most of the liquid has evaporated and the vegetables are tender but still hold their shape, about 15 minutes, stirring occasionally. Season the caponata to taste with salt and pepper. Spoon the caponata into a large bowl and cool to room temperature; there will be 5 cups. Cover and refrigerate overnight to allow the flavors to meld. Caponata keeps, covered, in the refrigerator for 5 days.
To serve, bring the caponata to room temperature. Spoon 1/4 cup of the caponata onto each crostino. If desired, garnish with a sprinkling of pine nuts or chopped parsley. Serve the remaining caponata as a side dish.