Place the beef or lamb in a skillet (not the one you are building your polo in) and brown with the carrots, onion and spices, draining off excess fat.

Stir in the tomato products, lemon juice, and water along with the green beans, which should be cut into 2-3" bite sized pieces.

Use a mandolin slicer to thinly slice potatoes and layer them in the pan in a few tablespoons of oil in an overlapping spiral fashion. Or slice them as thin as you can.

Place the saffron in a heatproof cup with the boiling water, making sure the saffron submerges. Give it about ten minutes to steep and bloom, same way you might make hot tea.

On top of the potatoes, layer half the rice being careful not to move the potatoes. Drizzle your rice with half the saffron water.

Top with the meat sauce, and the remaining rice and saffron water.

Pat down gently, and seal the pan with foil.

Heat on low for about 45 minutes. You should hear sizzling and smell those potatoes when it's about done- otherwise give it another 5-10 minutes.

Remove from heat and quickly line beneath the foil or lid with paper towels. And recover with foil or the lid. Let that rest 10-15 minutes to finish the rice cooking and absorb bits or extra moisture.

To serve, this whole thing is inverted sort of like a Bundt cake. It is heavy though so get a helper or strong assistant to turn the pan since it is very hot. Otherwise, serve with a spatula and turn it over as you serve so you can see your potatoes.