Heat oil in a pan, add mustard seeds and once they start to splutter, add the onions and garlic. Cook till the onions turn translucent.
Add the Brussels sprouts and turmeric. Cook till the sprouts are almost cooked through, about 8~10 minutes.
Add the tomato, garam masala, red chili powder and salt. Cover and cook till the tomatoes turn mushy.
Add the coconut milk, almond butter and some water; bring to a simmer and cook for 3~4 minutes. Adjust the seasoning and serve with rice or bread.