To prepare dough: Stir water, yeast, sugar and salt in a large bowl; let stand until the yeast has dissolved, about 5 minutes.
Stir in whole-wheat flour, all-purpose flour and polenta or maize flour (depending what you bought) until the dough begins to come together.
Turn the dough out onto a lightly floured surface. Knead the dough until it becomes smooth and elastic, about 10 minutes.
Place the dough in an oiled bowl and coat with the olive oil. Cover with a clean kitchen towel and set aside until it has doubled in size, about 1 hour.
Preheat the oven to 160°C / 325°F / Gas mark 3.
Line a large baking tray with greaseproof paper and set aside.
Turn the dough out onto a clean, lightly floured surface. Dust the top with flour; press into the dough with your fingers to flatten out.
Use a rolling pin to roll the dough into the thickness desired.
Place beans, peppers, garlic, chili powder and salt in a food processor and whizz until smooth.
Sprinkle maize or polenta flour onto the large baking sheet.
Transfer the dough onto the baking tray.
Place the baking tray with the rolled out dough, into the oven until lightly browned, roughly 3 to 4 minutes.
Using a large spatula, flip the cooked pizza dough.
Spread the bean mixture on the crust, leaving a 1-inch border.
Layer on the cheese, tomatoes, scallions, olives and jalapeños.
Return to the oven until the cheese has melted and the bottom of the crust has browned, about 8 minutes.
Slice into pizza slices and serve.