Step 1

Place a rack in middle of oven; preheat oven to 425°. Lightly coat the cups of a standard 12-cup muffin pan with nonstick spray. Using an electric mixer on medium-low speed, beat oil, butter, granulated sugar, and brown sugar until smooth, about 2 minutes. Scrape down sides of bowl and beat again just to incorporate. Add eggs, increase speed to medium, and beat until incorporated, about 1 minute (mixture might look a little curdled at this point and that’s okay). Add baking powder, baking soda, salt, and vanilla and beat until combined and creamy.

Step 2

Add flour in 3 additions, alternating with sour cream in 2 additions, beating on low speed after each addition until just combined. When last batch of flour is nearly incorporated, mix in any remaining dry bits by hand.

Step 3

Scoop 1 heaping Tbsp. batter into each muffin cup. Using a damp finger, flatten each into a mostly even layer with a slight dip in the center. Add 2 scant tsp. jam to each center, then divide remaining batter evenly among cups (about 2 Tbsp. each). Take care to seal in jam as much as possible. Using a damp finger, gently flatten surface. Bake muffins until golden brown, 17–19 minutes. Transfer to a wire rack and let cool 10 minutes in pan.

Step 4

While the muffins are cooling, melt butter in a small saucepan over medium heat; set aside.

Step 5

Finely grind strawberries in spice mill or with mortar and pestle. Transfer strawberry powder to a small bowl and mix in sugar and a pinch of salt. Transfer a small portion to a shallow bowl.

Step 6

Gently remove muffins from pan; place on wire rack and set inside a rimmed baking sheet. Brush sides of a muffin with butter and roll in strawberry sugar to coat. Brush top with butter; sprinkle with more strawberry sugar, working over bowl to catch any excess. Repeat with remaining muffins, adding more strawberry sugar to bowl as needed. (Save leftover sugar in an airtight container for another use.)Do ahead: Muffins can be made 3 days ahead. Store loosely covered at room temperature.