To make the dressing, whisk all the ingredients together in a jug and season with salt and pepper to taste. Add a little more palm sugar if needed. Set aside.
Tip the beaten egg onto a plate and coat the tofu in it. On a separate plate, mix together the cornflour, sesame seeds and salt and pepper and dip the tofu pieces into it. Set aside.
Heat the oil in a wok or large frying pan and very carefully shallow fry the tofu pieces for 2 minutes on each side. Remove from the pan, drain and keep warm.
Add the broccoli to the pan and cook for 2-3 minutes until starting to colour and soften a little. Splash over the soy sauce and griddle for another few minutes until tender, but retaining a little bite.
Add the spring onions, carrot ribbons and avocado and toss with the herbs, cooked broccoli and dressing. Divide among 4 serving plates, lay the tofu over the salad and sprinkle with some herb leaves. Serve with lime wedges for squeezing and extra soy sauce and black sesame seeds.