Pop the bulgar wheat in a large heatproof bowl. Season. Add 300 ml boiling water to the bowl. Cover with a saucer. Put to one side for 15 mins to soak.
Heat your grill to medium. Line the grill pan with foil. Finely grate the zest from the lemon and set it aside. Slice one half of the lemon thinly (save the other half for later). Grill the slices for 3-5 mins, turning once, till they're just charred on both sides. Put to one side to cool, then chop into small pieces.
Trim and thinly slice the spring onions. Trim the leaves off the radishes and keep them to one side. Halve, quarter or slice the radishes, depending on how large they are.
Roughly chop the tomatoes. Finely dice the flesh. Halve the chilli. Flick out the seeds and white bits. Finely slice the chilli.
Roughly chop the dill and radish leaves, discarding the thick stalks from the dill.
Fluff the bulgar wheat with a fork and stir in the chopped veg, herbs and lemon along with the lemon zest. Squeeze the juice from the remaining lemon half. Whisk the juice with 1 tbsp olive oil and a little salt and pepper. Stir through the bulgar wheat.
Flake the salmon off the skin. Roughly chop the salmon. Stir it into the bulgar wheat and set the salad aside for 5-10 mins to let the flavours develop. Taste and add more salt and pepper if it needs it, then serve.