Add the water to a large mixing bowl then sprinkle on the yeast. Stir in the flour, cornmeal, salt, and 2 TBSP of the olive oil and to stir until well combined and a dough is formed.
Knead the dough while in the bowl by hand for about 5 minutes then form into a smooth ball. Place the dough ball into a large clean bowl and drizzle the 1 tsp of oil over top. Flip the dough ball around a few times to cover the outside of the dough in the oil.
Loosely cover the bowl and set in a warm place to rise until doubled in size, about 1 hour.
THE TOPPINGS:
Add the ground beef and onion to a saute pan over medium-high heat. Cook, while breaking up the beef with a spatula, until beef is browned, about 8 minutes.
Stir the garlic, chili powder, cumin, and salt in with the beef until well combined. Stir in the water and bring to a boil.
Reduce the heat to medium-low and cook, stirring occasionally, until thickened, about 5 minutes. Take the pan off the heat and set aside.
THE ASSEMBLY:
Preheat the oven to 475°F. Lightly oil an 18x13-inch rimmed baking sheet and set aside.
Punch down your dough and stretch it to fit inside the baking sheet.
Bake the dough in the preheated oven for about 10 minutes.
Take the dough out of the oven and spread the beef mixture evenly over top then sprinkle the cheese evenly on top of the beef.
Place it back in the oven and bake until cheese is melted about 5 minutes.
Transfer the pizza to a cutting board and sprinkle the lettuce and tomatoes on top.
Slice the pizza into squares then top with sour cream and hot sauce. Eat the slices like a pizza or fold the slices and eat like a taco.