Pierogi With Caramelized Onions & Red Peppers

• 2 peppers (red)
• 1 parsley springs for (garnish)
• 450 gr potato cheddar pierogi (frozen)
• 30 ml salad oil
• 10 ml wine vinegar (red)
• 8 gr sugar
• 3 gr all purpose flour
• 1 gr coarsely black pepper (ground)
• some salt