Grease mini muffin cups. In a large bowl combine the dry ingredients. Add the egg, milk, lemon juice, oil, and the chopped walnuts. Mix until moist. Do not overbeat. Pour the batter into the prepared muffin cups. Bake in a 400 F oven for about 10 minutes, until a toothpick inserted in the center comes out clean. Glaze: Mix 1/4 cup lemon juice and 1/2 cup sugar. Spoon on top of hot muffins. Cool.