Set a medium pot of water on the stove and bring it to a boil over high heat.

While the water heats, pat the tofu dry with paper towels. Cut it into 1-inch cubes and set it on a plate.

Cut the potatoes into thin matchsticks so they cook quickly in the skillet. Slice the onion, bell pepper, scallions, and garlic if you have not done that yet.

Add 1 teaspoon of the salt to the boiling water. Put the potatoes into the pot and cook them for 4 minutes, until they are just starting to soften but are not fully tender.

Drain the potatoes in a colander. Let them steam off for 1 minute so excess water can evaporate.

Set a large skillet over medium-high heat and add 1 tablespoon of the oil. When the oil looks loose and shiny, add the tofu in a single layer.

Cook the tofu for 3 to 4 minutes without moving it much, until the bottom is golden.

Turn the tofu pieces and cook for 3 to 4 minutes more, until several sides are browned. Transfer the tofu to a clean plate.

Add 1 more tablespoon of oil to the same skillet. Put the drained potatoes into the skillet and spread them into an even layer.

Cook the potatoes for 4 minutes, stirring only once or twice, until they pick up some golden edges.

Add the onion, bell pepper, and scallion whites to the skillet with the potatoes. Sprinkle in the remaining salt and cook for 3 minutes, stirring often, until the onion starts to soften and the pepper turns bright green.

Add the garlic, ground cumin, and crushed red pepper to the skillet. Stir for 30 seconds, just until the garlic smells fragrant and the cumin coats the vegetables.