Preheat oven to 425 degrees F. Lightly coat a muffin tin with baking spray or line with paper cups. (This recipe usually yields 10 regular-sized muffins.)
To make the topping, melt butter in a small microwave-safe bowl. Add the flour, sugar, almonds, and salt, and stir with a fork to combine into a crumbly streusel. Set aside.
Combine the egg, sugar, and oil in a large mixing bowl. Whisk vigorously for 30-45 seconds, until the mixture is thick and slightly frothy.
Add vanilla and almond extracts, vinegar, baking soda, and salt. Whisk to combine.
Add sour cream, whisk to combine, then gently stir in the flour. The batter will be thick and slightly lumpy. Gently stir in the blueberries.
Divide batter evenly among muffin cups, filling each about 3/4 full, and sprinkle the streusel evenly over the top. Bake at 425 for 5 minutes, then, without opening the oven door, reduce the temperature to 350 and bake for another 12-14 minutes. When done, the muffins will be lightly golden on top and a toothpick inserted into the centers will come out clean.
Let cool for about 10 minutes in the pan, then remove to a wire rack to cool completely.
Notes
Storage: Muffins keep well at room temperature at least 2-3 days. I usually store them in an airtight container, leaving the zipper or lid slightly cracked, because they are very moist and this prevents any build-up of water droplets.
Freezer: Yes, these can be frozen! For best results, place fully-cooled muffins on a plate or sheet pan so they're not touching, then put that whole plate in the freezer for about 30 minutes. This will "flash freeze" the muffins so they don't stick together. Then transfer them all together into a large freezer-safe bag; no need to individually wrap. Defrost in the fridge overnight, then warm briefly in the oven or microwave right before serving.