Divide the cauliflower into large inflorescences and boil (I put it in boiling, salted water, let it boil and in a minute already threw it in a colander, we like the cabbage to remain a little hard). Allow to cool.
Onion cut into half rings. Very small cucumbers cut in half lengthwise, larger-along the four parts.
Cool cabbage disassemble into small inflorescences.
Combine in a convenient mixing bowl cabbage, onions and cucumbers.
For the dressing, mix the vegetable oil and mustard with the grains. Stir.