Peel bananas and cut into 1/2-inch slices; set aside.
Melt butter with brown sugar and water in a large skillet over medium heat until bubbling.
Arrange banana slices in a single layer. Cook 1–2 minutes, until the undersides turn golden.
Flip gently and cook 1–2 minutes more, just until lightly caramelized.
Stir in cinnamon, vanilla, and salt. Toss gently and simmer 30–60 seconds to thicken.
Remove from heat. Add lemon juice, if using. Serve warm with the pan sauce.