To make the focaccia:

• Mix together the yeast, cane juice, and warm water in a medium-size bowl.
• Let proof for about 10 minutes; it should foam and bubble up.
• If it doesn’t, start over again because your yeast might not be fresh.
• In a large-size bowl, combine the flours, onion powder, basil, salt, and pepper.
• Add the yeast mixture and begin to knead.
• If the dough is too dry, add more water, 1 tablespoon (15 ml) at a time, until you can incorporate all of the flour.
• Knead for about 5 minutes, until you get a soft, elastic, uniform dough ball.
• Lightly coat the ball with oil, cover lightly with plastic wrap, and let rise for 45 minutes to 1 hour.
• To make the potatoes: Use your preferred type of potatoes, and slice them as thin as possible (using a mandolin or a sharp knife).
• Rinse the sliced potatoes in cold water to prevent discoloration.
• Preheat the oven to 350°F (180°C, or gas mark 4) and prepare a glass 9 × 13-inch (23 × 33-cm) baking dish by lightly greasing or spraying with nonstick cooking spray.
• To make the onions: In a large-size frying pan, heat the oil over medium heat.
• Add the onion and salt and sauté until translucent and beginning to brown, 5 to 7 minutes.
• Add the vinegar and continue to cook for 2 to 3 more minutes, tossing to coat.
• Remove from the heat.
• Punch down the dough.
• Press the dough into the baking dish, making sure you get it into the corners, and create dimples in the surface with your fingers.
• Using a fork, poke holes all over the surface of the dough.
• Spread the minced garlic over the dough, then drizzle with olive oil.
• Layer the potatoes on top to cover completely, and spread the béchamel sauce all over the potatoes.
• Top with the balsamic caramelized onions.
• Bake for 1 hour, or until the potatoes are fork-tender and the edges of the focaccia are beginning to brown.
• Let cool before slicing and serving.