1.Make orange dressing. Simmer juice in a small saucepan, uncovered, for 8 minutes or until reduced to ¼ cup. Transfer to a small bowl; whisk in garlic, vinegar and oil until combined. Season to taste.
2.Place zucchini, oil and oregano in a medium bowl; season, toss gently to combine.
3.Heat a barbecue (or chargrill pan or grill) to high. Barbecue zucchini for 2 minutes each side or until browned and almost tender.
4.Layer witlof, fennel, zucchini, orange and beetroot on a platter or shallow serving bowl. Season to taste. Sprinkle with feta and drizzle with orange dressing. Top with reserved fennel fronds.
As you slice or shave the fennel, drop it into a bowl of iced water to make it crisp. You will need about 6 oranges for this recipe.Note