Roast Beef Tea Sandwiches with Red Onion Marmalade

Using a serrated knife, cut croissants in half horizontally. Spread a thick layer of Red Onion Marmalade onto bottom half of croissants. Divide roast beef slices among sandwiches. Top beef with rocket and cover with top half of croissants. Serve immediately, or cover with a damp tea towel or paper towels and refrigerate until ready to serve.