For best results, use fresh, ripe strawberries. If using frozen strawberries, thaw them completely and pat them dry before folding them into the batter. Turbinado sugar adds a lovely caramelized flavor and a slightly crunchy top, but you can substitute it with regular granulated sugar if desired. To add a nutty flavor, consider adding 1/2 cup of chopped walnuts or pecans to the batter along with the strawberries. Store leftover muffins in an airtight container at room temperature for up to 3 days, or in the refrigerator for up to 5 days.