Warm tuna, pasta and parsley salad

Ingredients

• 250 g cherry tomatoes
• 1 large red onion (cut into wedges)
• 2 garlic cloves (sliced)
• 1/4 cup pine nuts
• 1 tbsp olive oil
• 300 g penne or other pasta shapes
• 2 1/2 170g cans tuna in water (drained)
• 1 199ml can corn kernels (drained and rinsed)
• 1/2 cup fresh flat-leaf parsley (chopped)
• 1 lemon (juiced)
• 1/3 cup extra virgin olive oil
• 2 tsp whole grain mustard
• 1 tbsp bottled capers (rinsed and roughly chopped)