Peel and finely chop the onion. Pop in a pan with 2 tbsp warm water. Season with salt and pepper. Cover. Cook over a low heat for 5-8 mins till soft. Stir every so often. If it looks like it’s sticking, add a splash more water.
Peel and grate or crush the garlic. Add to the onion with 1 tsp of the turmeric, 1 tsp of the garam masala and 1 tsp of the mild curry powder. Cook and stir for 1 min.
Stir in the tomatoes. Pour in 150 ml boiling water. Bring to a boil. Cover and simmer for 5 mins.
While the sauce simmers, chop the cauliflower into chunks. Pop in a food processor (see our tip if you don’t have one). Blitz for 1-2 mins to make cauliflower ‘rice’.
Pull off any large stalks from the watercress so you just have tender stems and leaves. Set aside.
Chop the hake into bite-sized pieces. Add to the pan. Cover and cook gently for 5 mins till the fish flakes easily. Taste and season with salt and pepper. Set aside with the lid on.
Tip the cauliflower into a separate pan. Pour in 100 ml boiling water. Cook over a medium heat for 4-5 mins till just tender. Drain if necessary. Season. Serve topped with the watercress and curried hake.