Cook the soba in a big pot of rapidly boiling salted water just until tender - but about 20 seconds before the pasta is done cooking add the broccoli to the pot. You want it to barely cook.
Drain and rinse under cold running water. Sprinkle with lemon zest and set aside.
In the meantime make the dressing by combining the cilantro, garlic, cayenne or red pepper flakes, salt, and olive oil. Blend in a food processor or chop by hand. Taste, adjust for more salt if needed and set aside.
Drain the tofu, pat it dry, and cut it into rectangles roughly the size of your thumb (1/2 inch thick and 1 inch long). Cook the tofu in a dry nonstick (or well-seasoned) skillet over medium-high heat for a few minutes, until the pieces are browned on one side.
Toss gently once or twice, then continue cooking for another minute or so, until the tofu is firm, golden, and bouncy.
Remove from skillet, let cool a bit and if desired cut into matchsticks.
In a large mixing bowl, combine the soba, broccoli and a couple big splashes of the cilantro dressing. Toss until well combined. Add the tofu and gently toss again, add more dressing and a couple pinches of salt if needed.
Turn out onto platter and crown with a couple pinches of cayenne and a squeeze of lemon juice.