In a small saucepan, place the stock over low heat just to warm it up. Don’t bring to a simmer—you just want to heat it, not reduce it. Also bring a medium saucepan of water to a boil.
In a medium skillet, heat the oil over medium-high heat. Add the tofu and fry until golden brown, then flip and fry on the other side until golden brown, about 5 minutes. Transfer to a plate and sprinkle with a pinch of salt.
Now, add the mushrooms in a single layer to the skillet and fry, undisturbed, until brown on the first side, about 2 minutes. Stir and fry on the other side until browned, 1 to 2 minutes more. Transfer to the plate with the tofu.
Meanwhile, in a bowl, combine the tahini, soy sauce, sriracha and vinegar. Mix well.
By now, your water should be boiling. Add the broccoli and simmer for a couple of minutes, or until tender and bright green. Use a slotted spoon to transfer the broccoli to a plate and add the ramen noodles to the pot. Simmer until tender, according to the package instructions. Drain.
Divide the tahini mixture between 2 large bowls. Ladle in the hot stock and stir to combine. Divide the noodles, tofu, mushrooms and broccoli between the bowls and sprinkle with some sliced green onion and sesame seeds, if using.
Serve with the bottle of sriracha on the side for those who like it especially spicy.