Roast Veg and Chickpea Salad

• 400 g tin chickpeas, drained
• 1 medium sweet potato, cubed
• 2 Portobello mushroom, slices
• 150 g cherry tomatoes
• 1 red onion, thinly sliced
• .5 cup parsley, roughly chopped
• 2 tbsp lemon juice
• .25 cup extra virgin olive oil
• 2 tsp dijon mustard
• 100 g haloumi, sliced