For the soup, heat the olive oil in a pan and gently fry the onion, garlic and ginger for 2-3 minutes, or until softened. Add the thyme and sweetcorn and fry for a further 1-2 minutes, then add the stock and bring to a simmer. Cook for 4-5 minutes, or until the sweetcorn is tender. Stir in the coriander and cream and process with a stick blender until smooth.
For the ravioli, place the flour, one of the eggs and olive oil into a food processor and pulse until the mixture comes together to form a dough. Tip out onto a floured work surface and knead to bring together. Roll out into a thin circle.
Mix the crab together with the herbs and lemon juice and place into the centre of the pasta. Beat the remaining egg in a small bowl and use to brush the edges of the dough. Draw up the edges of the dough to form a dumpling around the filling, then steam for 5-6 minutes, or until the pasta is cooked and al dente and the filling piping hot. Serve on top of the bowl of sweetcorn soup.