Mix strawberries, powdered sugar, Grand Marnier, and orange juice. Refrigerate until sugar absorbed. Whip ice cream until fluffy (whatever that means). Fold whipped cream into mixture. Fold ice cream into mixture. The relative proportions of Grand Marnier and orange juice is optional.
Recommendation: The whipped cream seems largely superfluous. Whipping the ice cream makes it possible to mix it immediately with the strawberries. You can, instead, make the dessert ahead and let the ice cream melt into the strawberries and mix just before serving.