Step 1: Preheat your oven to 180°C (350°F) to ensure even baking.
Step 2: Grease your muffin tin or line it with muffin cases.
Step 3: In a large mixing bowl, sift together the self-raising flour, caster sugar, and rolled oats.
Step 4: In another bowl, whisk together the sunflower oil, eggs, yogurt, vanilla extract, and lemon zest.
Step 5: Gradually add the wet mixture to the dry ingredients, stirring gently until just combined.
Step 6: Gently fold in the blueberries, being cautious not to mash them.
Step 7: Spoon the batter into your prepared muffin tin, filling each cup about two-thirds full, and sprinkle with extra sugar and oats.
Step 8: Bake for 20-25 minutes, or until golden brown and a toothpick comes out clean.
Step 9: Allow to cool in the tin for a few minutes before transferring to a wire rack.