Tear off 9 pieces of parchment paper, each 12 inches long, and set them aside.

In a large bowl, combine flour, salt, vinegar, and water (including the extra 2 tablespoons) to form a smooth dough.

Adjust the dough’s consistency if needed. If it’s too dry, gradually add more water, one teaspoon at a time. If it’s too sticky, add a little more flour.

Cover the bowl with plastic wrap and let the dough rest for 1 hour.

Divide the dough into 8 equal-sized balls. Lightly flour a pastry mat or counter top. Use a rolling pin to roll one ball into a thin circle with an 8-inch diameter. Don’t worry if the circle isn’t perfectly round; a rough circle is fine.

Use a pastry brush or spoon to spread the melted butter or margarine over the top of the dough.

Fold the dough in half so it’s a semi-circle shape, and brush the top of the dough with melted butter.

Fold the dough in half again, so it’s now a quarter-circle shape. Brush the top of the dough with melted butter.

Fold the dough in half one last time, so it’s in the shape of a wedge or piece of pie.

Place the dough between 2 sheets of parchment paper. Repeat the process with the remaining dough balls, separating each piece with a sheet of parchment paper.

Lightly flour the pastry mat or countertop again and remove the first piece of buttered dough from between the parchment paper.

Use a rolling pin to roll the dough into a rough square or circle (the shape doesn’t really matter, just aim for an even thickness).

Place the rolled-out dough back between 2 sheets of parchment paper. Repeat with the other pieces of buttered dough.

Heat a medium skillet over medium heat. Grease the pan with butter or olive oil spray.

Cook the kahi for 2 minutes on each side, or until golden.

Arrange kahi on a serving platter, and sprinkle generously with powdered sugar. Serve immediately. 

Kahi is best eaten fresh, but it can be stored in an airtight container at room temperature for 1 day, or in the refrigerator in an airtight container for 3 to 4 days. Reheat in the oven or toaster oven at 350F for 5 to 10 min to crisp it up.