Halve the zucchini crosswise. Cut the zucchini flesh off the seedy center and coarsely grate it in a food processor(or box grater). Discard the center. Grate the potato and onion. Transfer the zucchini, potato and onion to a colander and squeeze dry. Let stand for 2 minutes, then squeeze again. Move the veg. mixture to a large bowl. Add the matzo meal, egg, lemon juice, salt and pepper and stir to mix.
In a medium skillet, heat 2 tbls. of veg. oil until shimmering. Drop packed teaspoons of the zucchini mixture into the skillet and flatten them with the back of a spoon. Cook the latkes over medium high heat until the edges are golden, about 2 minutes. Flip and cook until golden on the bottom, about 1 minute. Drain on paper towels. Repeat with the remaining zucchini mixture, adding more oil to the skillet as needed.
Arrange the latkes on a platter and top each one with a dollop of sour cream and a little red pepper jelly. Sprinkle with the scallion greens. Serve warm. At the bash, Rachel added thin slices of smoked trout on top of the pepper jelly. You may do this if you wish. Use 3 oz. of smoked trout, coarsely chopped.