Step 1
Preheat oven to 180°C/160°C fan-forced. Wash beetroot. Pat dry. Wrap in foil. Place on a baking tray. Roast for 1 hour or until tender. Cool for 15 minutes. Meanwhile prepare remaining ingredients. Peel and discard skin from beetroot. Cut beetroot into 2 cm pieces.
Step 2
Combine spinach, onion, feta, walnuts and beetroot in a bowl. Toss to combine.
Step 3
Place orange juice, oil and mustard in a screw-top jar. Season with salt and pepper. Secure lid. Shake to combine. Add to beetroot mixture. Toss to combine. Serve on bread.