Preheat oven to 400°. Line a baking sheet with foil; place a wire rack on the baking sheet.
To prepare streusel, combine 3 tablespoons sugar, 2 teaspoons water, and pepper in a small bowl. Spread mixture evenly over both sides of bacon. Place coated bacon on rack; bake at 400° for 18 minutes or until done. Cool; finely chop.
Combine oats and 1 tablespoon flour in a small bowl. Stir in butter. Stir in 2 tablespoons chopped bacon; reserve remaining bacon. Set aside.
Reduce oven temperature to 350°. Line 12 muffin cups with paper liners.
To prepare muffins, weigh or lightly spoon 7.9 ounces (about 1¾ cups) flour into dry measuring cups; level with a knife. Combine 7.9 ounces flour, remaining bacon, ½ cup sugar, baking powder, salt, and baking soda in a large bowl; stir well. Combine beer, oil, vanilla, and egg in another bowl, gently stirring with a whisk. Add beer mixture to flour mixture, stirring just until combined. Evenly divide batter among muffin cups. Sprinkle streusel evenly over batter.
Bake at 350° for 18 minutes or until a wooden pick inserted in the center of muffins comes out clean. Cool in pan 5 minutes. Remove muffins from pan; serve warm, or cool completely on a wire rack.