Grease a baking sheet (approximately 9 by 13 inches) with olive oil.
Heat the first 5 ingredients in a heavy saucepan over medium heat until it reaches a simmer. Add the salt and pepper, just a bit at a time, and taste after each addition. Add polenta a little at a time, while whisking.
Switch to a wooden spoon and keep stirring. Continue to cook for about 5 minutes. Add Greek yogurt, turn off heat and stir well. Remove bay leaf. Pour onto baking sheet and smooth with a buttered or oiled rubber spatula.
Cover with plastic wrap, put on the top shelf of the refrigerator and chill for 4 hours. While polenta is chilling, make the Pomegranate Sauce.
Once the polenta has set, heat a heavy skillet over medium heat until very hot. While pan is heating, cut polenta into roughly 3-inch pieces, using cookie cutters, biscuit cutters or a metal spatula. Pour the uncooked polenta onto a plate and roughly coat both sides of polenta cakes.
When pan is very hot, add 2 tablespoons of olive oil and put 2 polenta cakes in the pan, gently shaking pan from side to side for about 20 seconds, to keep cake from sticking. Cook for about 5 minutes, until browned.
Gently flip polenta cake with a spatula and cook 2 to 3 minutes. Place on a plate. Serve with spoonfuls of sauce and garnish with thinly sliced green onions.
Place hibiscus flowers and white wine in a small, heavy saucepot. Let sit for 10 minutes.
Add pomegranate juice and bring to a simmer over medium heat. Cook uncovered for about 10 minutes, until reduced by half and liquid looks a bit syrupy. Remove flowers, allow them to cool and finely dice. Add back to liquid.
Stir in heavy cream and bring back to a simmer. Cook for about 10 minutes, until cream thickens a bit and starts to darken around the edges.
Remove from heat, add sugar and stir. Add butter and whisk continuously until all butter is incorporated into sauce. Add parsley and salt, to taste.
*Hibiscus flowers, also called Jamaica flowers, are available at natural food stores and Latin markets.