Get the water going: Fill a medium saucepan with water and bring it to a boil over high heat for the rice noodles.

Set a large soup pot over medium heat and add the neutral oil.

Sear the tofu: Put the tofu cubes into the soup pot in one layer. Cook for 2 to 3 minutes, until the bottoms look lightly golden.

Turn the tofu cubes and cook for 2 minutes more, until a second side is lightly golden.

Transfer the tofu from the soup pot to a plate and set it aside.

Build the broth: Add the scallion whites to the soup pot. Cook for 1 minute, stirring often, until they soften slightly.

Add the garlic and ginger to the soup pot. Cook for 30 seconds, stirring, until they smell fragrant.

Add the chopped pickled mustard greens to the soup pot. Cook for 2 minutes, stirring, so they warm through and lose some of their raw jarred edge.

Add the cherry tomatoes to the soup pot. Cook for 3 minutes, stirring once or twice, until some of the tomatoes start to split.

Pour the vegetable broth and soy sauce into the soup pot. Raise the heat to high and bring the broth to a boil.

Lower the heat under the soup pot to medium-low and simmer for 5 minutes so the tomatoes soften more and the broth picks up the tangy flavor of the greens.

Cook the noodles: Add the rice noodles to the boiling water in the saucepan. Stir once right away so they do not stick together.