Preheat the oven to 350°F (175°C) and line a muffin tin with paper liners.
In a large bowl, whisk together the flour, sugar, baking powder, baking soda, and salt.
In another bowl, mix the buttermilk, vegetable oil, and egg until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined.
Gently fold in the raspberries, being careful not to overmix.
Evenly distribute the batter into the prepared muffin tin.
Bake in the preheated oven for 18-20 minutes or until a toothpick comes out clean.
Remove from the oven and let cool in the tin for 5 minutes.
Transfer muffins to a wire rack to cool completely.
Dust with powdered sugar before serving, if desired.