Preheat oven to 350°C Line a baking sheet with parchment or a silicone mat.
In a medium mixing bowl, combine oil, sugar, and zest (food processor works great for this). Beat in lemon juice, then cornmeal, oats, and salt.
If your dough is droopy chill it for at least 30 minutes.
In a small bowl stir together topping ingredients (brown sugar, nuts, and lemon zest). Set aside.
Drop dough by rounded teaspoonfuls, at least 3 inches apart, onto prepared sheet. Using a small pointy spoon push a slight dimple into each dough circle and tip about 1/8 tsp topping into each depression.
Bake about 12 minutes, until cookies are thin disks with golden edges.