Peel the celeriac and onions. Chop the celeriac into chunks about 2cm in diameter and the onions into wedges.
Place on a baking tray and toss with the spices, black pepper and coconut oil. Slice the garlic in half horizontally, add to the celeriac and drizzle everything with olive oil.
Roast in the oven for 30 - 40 minutes until golden and the celeriac is soft. Transfer to a serving bowl and toss with lemon juice, zest and fresh parsley.