Feel free to swap almond butter, coconut butter, or even tahini for the peanut butter to change up the flavor.
Peel bananas and cut into 3/4-inch-thick slices. Place in a single layer on a baking sheet; freeze until solid, 2 to 3 hours.
Finely chop 1/2 pound of the strawberries. Combine chopped strawberries, sugar, syrup, and 1/4 teaspoon of the salt in a saucepan. Cook over medium heat until strawberries become syrupy, 3 to 5 minutes. Remove from heat and let stand for 10 minutes. Coarsely chop remaining 1 pound strawberries. Stir into cooked strawberry mixture.
Process coconut milk, frozen bananas, peanut butter, vanilla, and remaining 1/8 teaspoon salt in a high-powered blender or food processor on high until very creamy, stopping to scrape down sides and press bananas into blade as necessary. Serve banana mixture immediately for a soft-serve consistency, or store in an airtight container in freezer for a firmer texture. Serve with strawberry sauce and chopped peanuts.