Meanwhile, heat olive oil over medium heat; add pancetta and cook until edges are crispy. Stir in red onion and garlic and cook until soft, about 5 minutes. Remove from heat.
Add frozen peas to boiling pasta for the last few minutes of cooking. Ladle out 1/2 cup (125 ml) of pasta water and set aside.
Drain peas and pasta, then return to saucepan and top with pancetta mixture. Stir in lemon juice and mint, and season with Parmesan cheese and pepper. If dish is too dry, stir in pasta water a little at a time.
Per serving: 382 calories, 14 g protein, 10 g fat (3 g saturated fat), 63 g carbohydrates, 2 g fibre, 8 mg cholesterol, 138 mg sodium