Rukmini Iyer's Roasted Cauliflower With Mustard, Chilli & Lemon

Ingredients

• 1 medium cauliflower, cut into medium florets
• 1 small sweetheart cabbage, cut into 3cm chunks
• 1 red onion, thickly sliced
• 5 tbsp natural yogurt
• 1 large red chilli, finely chopped
• ½ lemon, juice only
• ½ red chilli, chopped
• coriander leaves, to serve
• 4 heaped tbsp grainy Dijon mustard
• 2 tbsp neutral or olive oil
• 1 tsp sea salt flakes, plus extra to taste