In a large bowl, combine flour, sugar, poppy seeds, baking soda and the zest from two lemons. (reserve lemons for the juice)
In a smaller bowl combine sour cream, butter, eggs, vanilla, and juice from 1 of your lemons, reserving the other for the glaze.
Add your wet ingredients to your dry ingredients, stir just till combined. Pour mixture into loaf pan.
Preheat oven to 350 degrees, spray a 5"X9" loaf pan with cooking spray (I use the one with flour already in it), or you may use a muffin pan. Cook for 40 minutes, or until golden brown and toothpick comes out clean.
Allow to cool for about 10 minutes, while you prepare the glaze.
Glaze: Squeeze juice from other lemon into a glass measuring cup and add equal parts sugar. (I got about 1/4C from my lemon, so I added 1/4C sugar to it) Place in microwave and heat till sugar is dissolved.
Using a skewer, poke holes in bread and ladel glaze over the top of the bread to soak down into holes. Allow to cool completely on wire rack.