1. Heat oven to 375 degrees F. Grease 36 mini (1-3/4-inch) muffin-pan cups. Combine flour, 3/4 cup of the sugar, the poppy seeds, lemon peel, baking powder, baking soda and salt in medium bowl.
2. With pastry blender or two knives, cut in butter until mixture resembles coarse crumbs. Stir in milk, yogurt, egg and vanilla just until dry ingredients are moistened. Spoon batter into prepared muffin-pan cups; sprinkle tops with remaining 1 tablespoon sugar.
3. Bake 12 to 15 minutes or until toothpick inserted in center of muffins comes out clean. Unmold muffins and cool on wire racks. Makes 36.