Heat Oil in a pan and add mustard seeds and wait for it to crackle. Now add crushed garlic and chopped Onions along with curry leaves,when the onions become soft, add turmeric powder,salt and pepper powder.
Now add Broccoli and keep the pan covered for 5 mins. When the broccoli is cooked, add cabbage and stir fry it. Try to avoid over cooking the cabbage. Serve hot with rice.