Kielbasa With Peppers, Onions, & Mashed Potat

• 2 bell pepper (red)
• 1 scallion
• 210 gr fleshed (yellow)
• 190 gr smoked kielbsas
• 120 ml water
• 60 ml milk
• 30 ml water (hot)
• 16 ml vegetable oil
• 8 gr butter (unsalted)
• 1 slice onion