Heat 2 tbsp olive oil in a 24 cm / 9.5-inch (4-quart / 3.8 L) pot over medium heat. Add the onion and a pinch of the salt, and cook for 5 minutes, stirring, until soft and translucent but not browned.
Add the potato and stock and bring to a boil, then reduce to a steady simmer with the lid slightly ajar. Cook for 10 minutes, until a cube crushes easily against the side of the pot.
While the potato simmers, toast the pumpkin seeds in a dry 20 cm / 8-inch skillet over medium heat for 3 minutes, shaking the pan, until they pop and smell nutty. Tip them onto a plate.
Stir the frozen peas into the pot, return to a simmer and cook for 3 minutes, until bright green and tender. Take the pot off the heat, stir in the wild garlic and let it wilt for 1 minute.
Blend straight away until completely smooth, about 1 minute with an immersion blender. For a countertop blender, work in two batches, fill the jar no more than halfway and hold a towel over the vented lid.
Stir in the lemon juice, the remaining salt and the pepper, then taste and adjust. Thin with a splash of hot water if it's thicker than you like. Ladle into 4 bowls, top with the toasted seeds and drizzle with the remaining 1 tbsp olive oil.