Place the cucumber, corn, shallot, and semi sun-dried tomato in a non-reactive bowl. Add the vinegar and sugar and toss. Leave to pickle for 30 minutes - it can be left to pickle at room temperature for up to 4 hours or stored overnight in the fridge.
Bring a large pot of salted water to the boil. Add the pasta and cook according to package instructions, until al dente. Drain.
While the pasta is still warm (not mandatory but adding while warm encourages the pasta to soak up the flavours), add it to the pickled cucumber mixture, along with the cornichons, pickle juice, black olives, olive oil, sea salt, black pepper, feta cheese and herbs. Toss to combine.
Eat immediately or cover and allow to sit for a few hours at room temperature before serving. When you are ready to eat, you can add a touch more olive oil to loosen it up.