Heat a large frying pan over medium-high. Add 1 tbsp oil, then 1 thinly sliced small red onion, 2 minced garlic cloves, 1/2 tsp mustard powder and 1/4 tsp hot-red-pepper flakes. Cook until onion starts to soften, 2 minutes.
Add 1 small-medium head cauliflower, cut into florets (about 8 cups), 1/2 cup water and 1/2 tsp salt. Cook, covered and stirring often, until tender-crisp, 5 to 7 min. Stir in 1/3 cup chopped cilantro.
A flavourful side dish with this vitamin-rich cruciferous vegetable. Cook to the preferred tenderness-crispness.