Wash the cauliflower florets thoroughly in salted water and drain. Keep aside.
In a kadai / wok, take 1-2 tsp of vegetable oil. Splutter the mustard and cumin seeds. Throw in the mashed garlic, saute for 30 seconds. Don''t brown / burn it.
Put in the florets and green peas, along with the spices and salt. Cover the wok with a fitting deep dish (thali) and pour a cup of water over the dish. This will dry cook the vegetables without adding water into the wok and the steam generated will also keep them from sticking to the bottom of the wok or burning.
After 10 minutes, carefully lift up the covering dish with a pair of tongs and check if the veggies are cooked. 10 minutes are enough for the dish to be cooked well, if the vegetables are fresh.
Check for salt and remove into a bowl. You may garnish with finely chopped coriander leaves.
Serve hot with chapatis or as a side dish with meat.