We make this at home all the time. It's great with a quick salad of spinach, fresh strawberries, red onions, and feta (and candied sliced almonds or pecans).
1/2 c sugar
1.5 t ground mustard
1/3 c red wine vinegar
1/2 t salt
1/8 c chopped white onion
1 c canola oil
1 t poppy seeds
Combine all in a blender EXCEPT poppy seeds. Stir in poppy seeds after.