Spanish omelette with saffron aioli

Ingredients

• 30 ml olive oil
• 500 g waxy potatoes, unpeeled, sliced
• 1 onion, finely sliced
• 1 sprig rosemary
• 1 garlic clove, bashed
• 6 large free-range eggs
• 2 tbsp whole milk
• Shaved Manchego cheese, flaked sea salt and chopped parsley, to serve
• For the aioli:
• 1 medium free-range egg yolk
• 1 garlic clove, crushed
• Small pinch saffron threads
• 1 tsp white-wine vinegar
• 75 ml olive oil
• 50 ml vegetable oil
• Juice 1⁄2 lemon, plus wedges to serve
• You will need:
• 20 cm frying pan