Begin by peeling the tomatoes. Cut a shallow x in the bottom of each tomato. Bring a pot of water, large enough to hold the tomatoes, to a rolling boil. While the water is heating, prepare a large bowl of ice water, and set aside. When the water boils, add the tomatoes, and after 30 seconds, remove the tomatoes with a slotted spoon and place them briefly in the ice water to stop the cooking process. Remove tomatoes from the ice water, and using your fingers, remove the skins.
Cut each tomato crosswise, and remove the seeds, using your finger or a spoon. Roughly chop the tomatoes, place in medium bowl, and set aside.
Roast the pepper on all sides, until charred all over. You can do this under the broiler in your oven, or on the stove top. Use a set of tongs to turn the pepper as it blackens on each side. Place pepper in a plastic bag, twist the top to seal, and place top down on the counter. Leave for 15minutes.
Remove the pepper from the bag. The skin should slip off. Seed and chop. Place in bowl with tomatoes.
Mince the garlic, and heat with the cumin and garlic in the olive oil over medium low heat, stirring, just until the scent of the garlic rises up.
Add the tomatoes and peppers, and cook, stirring often, until most of the liquid has evaporated. Taste and add preserved lemon if you like, and salt and pepper to taste.
Cool and refrigerate in covered container until ready to serve.