Thaw the strawberries, either by setting them out for several hours or microwaving on the defrost setting until no longer cool to the touch.
Puree the strawberries in a food processor or blender. If the mixture is still cold, defrost in the microwave until no longer cool to the touch.
Break the chocolate into squares and place in a microwave-safe bowl. Add the oil and microwave, stopping and stirring every 15 seconds, until the chocolate is completely melted. Do not allow the mixture to exceed 160°F A double boiler may be used to melt the chocolate mixture if you prefer.
Add 1/2 cup strawberry puree to the melted chocolate mixture and stir until smooth. Microwave briefly if necessary until mixture is smooth.
Fill a large bowl with ice cubes and water. Set the bowl with the melted mixture directly in the ice water. Be careful not to get any water into the bowl. Stir constantly with a spoon or whisk until the mixture becomes thick and holds stiff peaks. Immediately remove from the ice water.
Allow the buttercream to sit for several minutes. If it has become solid, it is too cold and will need to rest until it has returned to room temperature.
Beat the buttercream until thick and airy.