Garlicky mushrooms with baked beans

Ingredients

• 2 tbsp lemon juice
• 1 tbsp olive oil
• 1 tsp Dijon mustard
• 1 tsp vegetable oil
• 1 tbsp apple cider vinegar
• 1 tsp dried mixed herbs
• 2 cloves garlic crushed
• ½ onion peeled and diced
• 400g (14oz) can chopped tomatoes
• For the mushrooms:
• 4 large Portobello mushrooms
• 3 tbsp chopped parsley 
• For the baked beans: 
• 400g (14oz) can cannellini beans drained