Combine potatoes, onions, a generous amount of salt and pepper in a bowl, and mix well. Heat oil over medium-high heat until hot in a 10-inch nonstick skillet. Add potatoes, shaking and turning to cover evenly with oil. Once a few slices begin to brown, press potatoes with a spatula to flatten into a disk. Adjust heat to medium-low, cover tightly, and cook until several slices are golden brown on the bottom, about 5 to 7 minutes. Carefully lift off cover so condensation does not fall on potatoes, and wipe dry. Mix cooked slices into other potatoes, recover, and cook until bottom of galette is golden brown, about 5 minutes longer. Shake pan to loosen, if stuck. Slide galette onto a plate, cover with a second plate of the same size, invert, then slide back into pan. Do not worry if some slices need rearranging. Flatten potatoes again, and cover. Cook 10 to 12 minutes longer, removing lid after 5 minutes, or until potatoes are golden brown, adjusting heat up slightly if needed to color potatoes. Slide onto plate and season with salt and pepper. Cut into wedges. Combine parsley and garlic with Pomodoro Sun-Dried Tomato Spread, and serve with potatoes. Slicing potatoes into 1/16th inch slices is easily done with a food processor using a 2 X 2-mm slicing blade.