Vegetable samosas

Name: Vegetable samosas
Ingredients: 2 tsp ghee; 1/2 tsp mustard seeds; 1/2 tsp cumin seeds; 1/2 small onion, peeled and finely diced; 1 bird's eye chilli, finely chopped; 1 clove garlic, peeled and finely chopped; 2cm piece of ginger, peeled and finely chopped; 1/2 cup frozen baby peas; 1 potato, peeled and finely diced; 200g cauliflower (about ¼ head), broken into small florets; 1/2 carrot, peeled and finely diced; 2 tsp curry powder; 1/2 cup water; 1/2 tbsp lemon juice; 1 tsp salt; 250g pack frozen spring roll pastry, thawed