Hull all but four of the strawberries. Add the hulled strawberries to a food processor or blender. Add the yogurt, orange juice, and sugar. Process on the highest speed until a well-blended puree forms, about 15 seconds, stopping to scrape down the sides of the container once or twice. Taste the mixture and sweeten with more sugar, if you wish.
Pour into tall glasses. Slit the four whole strawberries and the orange slices halfway through to the centres. Attach one strawberry and one orange slice, if using, to the rim of each glass before serving.