Heat 1/4 cup of olive oil in a large, heavy bottom sauce pot or Dutch oven, over low heat. Add the onions and cook, stirring frequently for about 10 minutes or until the onions are wilted. Add the minced garlic and stir until fragrant. Season with pepper. Increase the heat to medium and add the wine. Cook, stirring occasionally, until the wine is mostly reduced, about 20 minutes. Crust the tomatoes into the pot (by hand) along with any canned juice. Add the tomato paste, sugar, red pepper flakes and 2 cups of warm water. Simmer, stirring occasionally, uncovered, for 1 hour.