Heat oven to 375F (convection bake or roast if possible).
Break up the cauliflower in florets.
Chop or tear the red cabbage into large chunks, removing the core.
Clean the Brussels sprouts and cut in half lengthwise.
Cut the broccoli into long filets or break up in florets.
Mix all the veggies together with macadamia nut oil and mustard seeds and toss on a sheet pan, or roast on individual sheet pans depending on the presentation and how well you want each item to be roasted.
Roast 10-20 minutes until crispy and lightly browned.