Combine the strawberries, sugar and lemon juice in a saucepan and bring to a boil over medium heat. Adjust sweetness if necessary with more sugar. When the sugar is dissolved, lower heat to a simmer and let it cook for about 5 minutes. Remove from heat and chill until completely cool.
Take 1/2 of the sauce and stir together with the vanilla yogurt and Greek yogurt. Pour into the pre-frozen bowl of your ice cream maker and churn for about 30 minutes, or until it has achieved a thick, frozen yogurt consistency. Enjoy immediately or store in a tightly sealed container in the freezer. Serve with remaining strawberry sauce.