How to Make It
Thinly slice about half of 1 rhubarb stalk into 1/8-inch-thick half-moons to yield 1 cup. Set aside. Chop remaining rhubarb stalks into 1/2-inch pieces.
Heat oil in a large skillet over medium. Add panch phoron; cook, stirring often, until sizzling and fragrant, about 2 minutes. Stir in chopped rhubarb, brown sugar, ginger, vinegar, and chile powder. Reduce heat to low; cook, stirring occasionally, until mixture is jammy and reduced to about 11/3 cups, about 25 minutes. Stir in salt. Transfer chutney mixture to a bowl. Let cool, then refrigerate until ready to use.
Toss together strawberries and torn mint in a medium bowl; if strawberries are sweet, add lime juice. Season to taste with salt.
To serve, spread 1 tablespoon chutney in a 4-inch circle on each of 4 plates. Arrange strawberry mixture evenly on top of chutney; top with rhubarb half-moons and masala boondi. Sprinkle with chaat masala; garnish with mint leaves.