Step 1 Bring a large saucepan of water to the boil. Add corn-cob halves to pan and cook for 4–5 minutes, or until tender; set aside.
Step 2 Heat half of the olive oil in a large non-stick frying pan set over medium–high heat. Add sausages to pan; cook, turning occasionally, for 5–6 minutes, or until cooked through. Transfer sausages to a plate, cover loosely with foil to keep warm and set aside.
Step 3 Add three-quarters of the onion to same frying pan; cook, stirring, for 5 minutes, or until soft. Stir flour into onion, then stir in wine (if using), thyme and beef stock. Increase heat to high, bring to the boil and simmer for 5 minutes, or until gravy is slightly thick.
Step 4 Meanwhile, place a medium saucepan over medium heat. Add remaining olive oil and heat. Add remaining sliced onion and cook, stirring, for 5 minutes, or until soft.
Step 5 Add frozen peas to saucepan with 1 cup water and bring to the boil. Simmer mixture, uncovered, for 3 minutes, or until peas are tender. Blend onion–pea mixture and mint leaves in a small food processor until purée is smooth.
Step 6 Divide pea purée among plates. Top each with 2 sausages, spoon onion gravy onto sausages and serve with 1 corn-cob half.