Drain the tofu. Wrap each block in a double layer of paper towels and pat dry, pressing down on the tofu lightly to squeeze out excess moisture. Cut the tofu into 3/4-inch cubes.
In a large nonstick skillet or wok, heat the canola oil over medium-high heat. Once the oil is hot but not smoking, add the tofu (be careful, as the oil will splatter a little bit) and drizzle with 1 tablespoon soy sauce. Sauté, stirring every minute or so until the tofu is nicely colored on all sides and the moisture has cooked off, about 8 to 10 minutes. Don’t feel that you need to stir constantly. Sitting for a while on one side is what will allow the tofu to brown. Add the garlic, roughly two-thirds of the green onion, ginger, chili paste, and the remaining 2 tablespoons soy sauce. Stir and cook until fragrant, about 1 minute.
Add several large handfuls of spinach, stirring as you go so that it wilts and you can fit more in the pan. Once the first addition has wilted, continue to add and wilt the spinach by handfuls, until all of the spinach is added. It will seem like a ridiculous amount at first but will cook down considerably. Stir in the sesame seeds. Stir in the sesame oil. Remove from the heat. Sprinkle the reserved green onions over the top. Serve hot, with brown rice, noodles, or whatever you like, along with a few dashes of additional soy sauce and chili paste or flakes to taste.
*I don't recommend olive oil in stir fries at this high of heat, as its lower smoke point can cause it to burn, imparting an off flavor to the whole dish
**You can replace the spinach with any kind you prefer or have in your refrigerator. Spinach cooks ultra quickly, which is why in this recipe you can sauté it in the pan right with the tofu. For firmer vegetables, like broccoli or peppers, I recommend cooking the tofu as directed through Step 2, then removing it to a plate. Add additional oil (and garlic and ginger if you like) to the pan with your vegetables of choice. As soon as the vegetables are crisp-tender (about 5 to 8 minutes, depending upon the vegetable and how large they are sliced), add the tofu back to the skillet and proceed with the recipe as directed.
For crazy crispy tofu, prep it through Step 3 in my guide for How to Cook Crispy Tofu. Once you've boiled it, pat dry, dice into 3/4-inch cubes, and follow this tofu stir fry recipe as directed, starting with Step 2.
Refrigerate leftovers for up to 5 days. Reheat gently in the microwave. You can freeze this as well. The vegetables will become fairly soft and a bit mushy, but if that doesn't bother you (it certainly doesn't stop me), freeze away!