Tenderloin is one of the most tender cuts of beef so it's easy for kids to love it -- don't save it just for company! You can sub in carrots and/or parsnips for the sweet potatoes or brussel sprouts if you like.
Toss vegetables with 1 tbsp (15 mL) of the oil and season with salt and pepper; place in small foil-lined roasting pan.
Combine remaining oil, vinegar, maple syrup and mustard in small bowl; separate out 1 tbsp (15 mL) and brush it over the roast. Season roast with salt and pepper; place on top of vegetables. Insert meat thermometer into centre of roast.
Roast in 425F (220C) oven for about 1 hour or until thermometer reads 145F to 150F (63C to 66C) for medium-rare; remove roast from pan and let rest 10 to 15 minutes. Meanwhile, toss vegetables with remaining syrup mixture and continue roasting while roast rests.
Carve roast across the grain into thin slices and serve with roasted vegetables.