Preheat oven to 425°, or 400° if using a convection oven.
Trim the large leaves and any long pieces of the stem from the cauliflower. Cut them into one inch pieces.
Place all the chopped cauliflower in a large bowl or pot and drizzle with olive oil, cumin, salt and pepper. Use your hands to toss the vegetables with the olive oil; they should be lightly coated, but not drenched in oil.
Spread them onto parchment lined cookie sheets, spreading into a single layer (if they are piled on top of each other, they will steam instead of roast). Roast for 20 – 30 minutes, although you should begin checking them after 15 minutes when you may want to toss them again to avoid letting the bottoms burn. They should be taken out when they start to brown in spots and are just becoming tender. Adjust seasoning as necessary.