Prep the berries: Hull and dice the strawberries into small pieces (about blueberry size). Toss with 1 tablespoon flour.
This helps prevent them from sinking and keeps the muffins from turning soggy.
Preheat the air fryer: Set it to 320°F (160°C) for 3–5 minutes. A warm basket helps the muffins rise evenly.
Mix dry ingredients: In a medium bowl, whisk flour, sugar, baking powder, baking soda, and salt until well combined.
Mix wet ingredients: In another bowl, whisk yogurt, milk, oil, egg, and vanilla until smooth.
Combine gently: Pour the wet mixture into the dry. Stir with a spatula until just combined.
It’s fine if a few streaks of flour remain. Overmixing makes muffins tough.
Fold in strawberries: Add the floured berries and fold gently to distribute. The batter will be thick.
Line the cups: Place silicone or paper liners into an air fryer–safe muffin tin or use freestanding silicone cups.
Fill each about 3/4 full. Sprinkle tops with coarse sugar if you like a crunchy lid.
Air fry in batches: Arrange cups in the basket, leaving space for air to circulate. Cook at 320°F (160°C) for 12–15 minutes, until the tops are set and a toothpick comes out with a few moist crumbs.
Cool briefly: Let muffins rest in the basket for 2 minutes, then move to a rack to cool another 10 minutes.
They continue to set as they rest.
Repeat: If you have more batter, repeat with the remaining cups. Keep timing consistent but check a minute early, since baskets hold heat.