Lentil dal sandwich

Ingredients

• 120g red lentils
• 300ml reduced-salt vegetable stock
• ½ red onion
• 1 medium carrot, peeled and diced
• ½ teaspoon turmeric
• ½ teaspoon dried coriander
• ½ teaspoon cumin
• ½ –1 teaspoon curry powder
• 1 clove garlic, crushed
• 2cm root ginger, peeled and grated
• 150ml coconut non-dairy milk
• 1 teaspoon vegetable oil
• ½ teaspoon mustard seeds
• Handful fresh coriander, finely sliced
• Freshly ground black pepper
• 2 heaped tablespoon fat-free Greek yoghurt (non-dairy optional)
• 4 leaves fresh mint, finely sliced
• 1 teaspoon lemon juice (optional, to taste)
• 10 x slices wholemeal bread
• 125g cucumber, cut into thin slices
• 50g baby spinach