Preheat the oven to 350 degrees F. Lightly coat a large casserole dish with nonstick spray. Set aside.: You will notice the kitchen warming as the oven comes to temperature, a faint dry heat that hints the meal is moving toward completion. Preheating ensures even baking so the sauce bubbles and the tortillas crisp gently at the edges; putting the pan into a cold oven can produce uneven heating and soggy tortillas. A common mistake is skipping the nonstick spray, which can make portions stick to the dish when serving, so take a moment to coat the pan thoroughly.
Prepare the enchilada filling: Place the tofu in a food processor and puree for several minutes until smooth, stopping to scrape down the bowl as needed. Sprinkle in the salt, turmeric, black pepper, and cayenne. Pulse a few more times to mix well.: Place the tofu in a food processor and puree for several minutes until smooth, stopping to scrape down the bowl as needed. Sprinkle in the salt, turmeric, black pepper, and cayenne. Pulse a few more times to mix well. : As you puree the tofu , the texture transforms from chunky to velvety, releasing a faint nutty scent and a hint of earth from the spices. This smooth base helps bind the other ingredients, creating a creamy mouthfeel that contrasts the firmer black beans . If the tofu seems watery, blot with paper towel before processing. A common slip here is under pureeing, which leaves uneven chunks that can cause the filling to fall apart when rolling.
Heat the 2 tablespoons oil in a deep skillet over medium. Once hot and shimmering, add the jalapeno, bell pepper, and onion. Cook, stirring occasionally, until the vegetables soften and begin to brown, about 5 minutes. Stir in the tofu and nutritional yeast, if using, and continue cooking and stirring until the tofu is heated through and dries somewhat (it should look similar to scrambled eggs), about 5 minutes. Stir in the beans and thawed, pressed spinach. Stir, breaking up the spinach as you go. Season with additional salt and pepper to taste.: When the oil shimmers you will smell the pepper and onion aromas bloom, and as they brown a sweet, caramelized fragrance develops. Stirring every so often helps encourage even color and prevents sticking. Adding the pureed tofu absorbs flavors and changes texture to something drier and scramble like, which helps the filling hold when rolled. A typical error is cooking over too high a heat, which can scorch the vegetables; keep the flame moderate and adjust as needed.
Spoon a thin layer of the enchilada sauce into the bottom of the prepared baking dish. Wrap the tortillas in damp paper or cloth towel and microwave for 30 seconds to make them more pliable. Scoop a 1/4-cup portion of filling into each tortilla (or whatever amount you desire), roll tightly, and place seam-side down in the prepared baking dish. Repeat with remaining tortillas. Spoon the remaining enchilada sauce over the top of the enchiladas. Lightly coat any exposed tortillas with a little nonstick spray or brush with olive oil so that they crisp nicely in the oven.: The sauce at the bottom prevents sticking and infuses the underside of the tortillas with flavor as they bake. Warming the tortillas makes them supple, eliminating cracks and tears when rolling. When scooping the filling you should feel a balance between firm and moist, and the rolled enchiladas should sit snugly in the dish without collapsing. One oversight I see is overfilling, which causes tearing and messy assembly, so keep portions measured and tidy.
Bake for 15 minutes, or until the sauce is hot and bubbly and the tortillas are golden. Serve with desired toppings.: As the tray bakes you will hear gentle bubbling from the sauce and see steam rise when you open the oven, along with a toasty scent from the slightly crisped tortilla edges. The visual cue is small browned edges and a glossy, active sauce. Let the dish rest a few minutes so the filling sets slightly before serving; cutting too soon can cause the sauce to run. Avoid leaving the enchiladas in the oven much longer than instructed, which can dry them out and diminish the fresh toppings' contrast.