Smoked Salmon Toast with Red Onion Sauce

Peel the and dice the onion. Heat the vegetable oil in a small pan and sauté the onion, mustard seeds and capers until the onions are softened. Add the vinegar and chopped dill, season with salt and pepper and simmer over medium heat for about 4 minutes. Spread the butter onto the toast slices, top with the lettuce and radicchio, and place a piece of the smoked salmon fillet on each. Spoon the onion sauce over the top and serve immediately.