In a medium bowl, stir together the potatoes, garlic, 3 tablespoons cornmeal, parsley and egg.
Heat the oven to 350 degrees. Form the potato mixture into rounds about 3/4-inch thick. Put the remaining cornmeal into a shallow dish.
Working in batches, heat 2 tablespoons oil in a large skillet over medium heat. Coat the potato cakes on each side in cornmeal, brown lightly on both sides in the skillet and transfer to a baking sheet. Repeat with the remaining potato cakes, adding more oil as needed between batches. Bake the cakes until heated through, about 5 to 8 minutes. Serve with cooked fresh or frozen peas and pea shoots for garnish.
To make mashed potatoes: Use 1 to 1 1/2 pounds peeled russet potatoes. Put in a pot with enough water to cover the potatoes by an inch. Add a generous pinch of salt. Set over high heat, bring to a boil, reduce the heat and simmer until the potatoes are very tender. Drain off any excess water. Mash the potatoes, adding warm milk or cream, and season with salt and pepper.
To make the yogurt sauce: Stir together 1 cup whole-milk Greek yogurt with 2 to 3 tablespoons chopped parsley and 1 teaspoon fresh lemon juice.