Preheat the oven to 200°C.
Arrange the potatoes in an oven proof tray, sprinkle with salt, drizzle with olive oil and toss.
Roast in a moderately hot oven for 25 minutes.
Combine Vegeta Gourmet stock powder with olive oil, lemon juice and mix to blend. Brush over the salmon.
Remove the potatoes from the oven and add the salmon, skin-side down. Continue baking for another 10-15 minutes. Meanwhile, make the sauce.
Sauce: Into a hot pan add butter, flour and sugar and stir until butter melts and blends with the flour. Add milk and continually stirring, bring the sauce to boil. Season with salt, add the lemon juice, mustard and horseradish and continue to simmer for a couple of minutes. Remove from the heat and add chopped dill and cream. Stir to combine and serve the sauce with salmon and potatoes.
Before placing the salmon into the oven, put a cup of water in the oven. The evaporating moisture will prevent the salmon from drying out.