Wash cabbage, and discard the 2-3 outer leaves. Quarter it, and then grate coarsely (cut out the thick root in the middle and discard) and place it in a larger bowl. Pour salt over it and mix well. Leave for 30-ish minutes until the cabbage sweats out its liquid.
Chop tomatoes into medium chunks. Add to the cabbage, and mix everything well together with the liquid the cabbage sweated out.
Make a vinaigrette by mixing juice from one lemon, oil, parsley, salt and pepper. Pour evenly over the salad and mix well.