Prepare the Biscuits:

1. Preheat Oven: Preheat your oven to 450°F (232°C). Line a baking sheet with parchment paper.

2. Combine Dry Ingredients: In a large bowl, whisk together the flour, baking powder, salt, and baking soda.

3. Cut in the Butter: Add the cold butter cubes to the flour mixture. Use a pastry blender or your fingertips to cut the butter into the flour until the mixture resembles coarse crumbs with some pea-sized pieces of butter remaining.

4. Add Buttermilk: Gradually add the cold buttermilk to the flour mixture, stirring until just combined. Be careful not to overmix; the dough should be shaggy.

5. Turn Out and Knead: Turn the dough out onto a lightly floured surface. Gently pat the dough into a ½-inch thick rectangle.

6. Cut Biscuits: Use a biscuit cutter or a knife to cut out biscuits. Place the biscuits onto the prepared baking sheet, close together for soft sides or farther apart for crispier edges.

7. Bake: Bake for 12-15 minutes, or until the biscuits are golden brown.

Make the Chorizo Gravy:

1. Cook the Chorizo: In a large skillet over medium heat, cook the beef or turkey chorizo, breaking it up with a spoon, until it is browned and fully cooked. Remove the chorizo from the skillet and set aside, leaving the rendered fat in the skillet.

2. Sauté Onions and Garlic: Add the chopped onion to the skillet with the chorizo fat. Sauté until the onion is softened and translucent, about 5 minutes. Add the minced garlic and cook for 1 minute, until fragrant.

3. Make the Roux: Sprinkle the flour over the onions and garlic in the skillet. Cook for 1-2 minutes, stirring constantly, to create a roux.

4. Add Milk Gradually: Slowly pour in the milk, whisking continuously to prevent lumps from forming. Bring the mixture to a simmer, stirring occasionally.

5. Season: Season the gravy with black pepper, red pepper flakes (if using), and salt to taste. Reduce the heat to low and simmer for 5-7 minutes, stirring occasionally, until the gravy has thickened to your desired consistency.

6. Combine Chorizo and Gravy: Return the cooked chorizo to the skillet and stir to combine with the gravy.

Assemble and Serve:

1. Serve: Split the warm biscuits in half and spoon the chorizo gravy generously over each half.

2. Garnish: Garnish with fresh cilantro, if desired, and serve immediately.