In a large bowl, combine flour and sugar. Cut in butter until crumbly; set aside.
In a large bowl, cream butter and sugar until light and fluffy. Beat in eggs. Beat in the sour cream, lemon juice and zest. Combine the flour, baking soda and salt; gradually add to creamed mixture just until moistened.
Fill greased or paper-lined muffin cups two-thirds full. Sprinkle with reserved crumb topping. Bake at 350° for 25-30 minutes or until a toothpick inserted in the center comes out clean. Cool in pans for 5 minutes before removing to wire racks.
Combine glaze ingredients; drizzle over muffins. Serve warm.