Eggplant and potato curry

Ingredients

• 1/2 cup (125ml) olive oil
• 9 baby eggplants, sliced thickly
• 2 medium (400g) potatoes, chopped coarsely
• 1/2 teaspoon cumin seeds
• 1 teaspoon brown or black mustard seeds
• 1 large (200g) brown onion, chopped
• 2 cloves garlic, crushed
• 2 piece (10g) fresh ginger, grated finely
• 2 long green chillies, sliced thinly
• 2 tablespoon medium curry paste
• 400 gram can diced tomatoes
• 1 cup (250ml) water
• 1 bunch english spinach, trimmed, chopped coarsely
• 1 teaspoon palm sugar or brown sugar salt