Pre-heat oven to 375 degrees. Butter muffin tins for 12 muffins. Sift the dry ingredients (flour and soda) and set aside. Cream the butter in a large bowl and add the sugar a little at a time, beating until light and fluffy; add the eggs one at a time, beating well, then add the lemon juice, vanilla, lemon peel and poppy seeds. Add the flour and sour cream to this making sure the batter is well mixed. Fill muffin tins about 3/4 full. Bake for 20-25 minutes or until golden. Dust with confectioners sugar and serve warm or cool on a cake rack. The original recipe calls for separating the eggs and whipping the egg whites separately with half the sugar. This meringue is then folded into the batter just before baking. This makes for a lighter muffin, but is unnecessary.