Place the bananas and strawberries in a food processor and process. The fruit will begin to look like dry crumbs, not a creamy soft serve. This is good. You may have to stop and stir the fruit a few times as the bananas often form a clump. (see notes)
When you reach the “crumb” stage, pour the sweetened condensed milk over the fruit mixture. (You may add everything at the beginning but I find some of the condensed milk tends to settle under the blade when it is added at the beginning.)
Enjoy immediately as you would soft serve ice cream or store in freezer. This will freeze hard like regular ice cream. When I make extra to store in the freezer, I let it sit at room temperature a few minutes to soften before serving.