Classic Moroccan shaved fennel and red onion with beetroot and orange

Ingredients

• 4 medium red beets, tops trimmed
• 3 blood oranges
• 1 navel orange
• 1 tablespoon fresh lemon juice
• 1 tablespoon fresh lime juice
• 1/2 fennel bulb, very thinly sliced crosswise
• 1/2 red onion, very thinly sliced (about 1/3 cup)
• Good-quality extra-virgin olive, pumpkin seed, or walnut oil (for drizzling)
• Coarse sea salt
• freshly ground black pepper
• 1/4 cup loosely packed fresh cilantro and/or chervil leaves