For the frozen rice milk
In a large mixing bowl, slowly whisk honey into rice milk. Freeze mixture in a shallow glass dish, stirring and scraping with a fork every 30 minutes, until firm but not frozen solid, about 2-3 hours. Keep in glass dish until ready to use.
For the plantains and assembly
Place the brown sugar, lemon juice, and lemon zest in a small pot over low heat. Whisk to combine and simmer, stirring occasionally, until the sugar dissolves and the mixture begins to thicken, about 10 minutes.
While the sugar simmers, prepare the plantains. Melt butter in a sauté pan over medium high heat. Add plantains and cook until golde on both sides, about 2 to 3 minutes per side. Pour brown sugar mixture over and carefully stir as to not smash plantains.
To serve, add a few pieces of plantain in a bowl with a spoonful of warm caramel sauce. Finish each bowl with a generous helping of frozen rice milk and a little sprinkle of chai masala, black mustard seed and flaky salt. Top with torn mint.