Potato-Bean Salad

This is an awesome side with just about anything.  It's a variation of regular potato salad.

1 lb potatoes, peeled and cut into 2-inch chunks (I've used just about every kind of potato, and usually leave the skins on)
1/2 lb fresh green beans, trimmed and halved
1 Tbs mustard
1/4 cup mayonnnaise
3 Tbs sour cream (or try greek yogurt for a lil heathier dish)
1 Tbs chopped fresh tarragon (or 1 tsp dried)
Juice of 1 lemon, plus 1 tsp grated zest
1/4 red onion, thinly sliced

Freshly ground pepper and salt to taste

1. Cover the potatoes with cold water in a saucepan and salt the water.  Bring to a boil over med-high heat and cook until tender, about 10 mins.  Transfer to a colander with a skimmer or slotted spoon.

2.  Add the green beans to the boiling water and cook until crisp-tender, about 3 minutes.  Transfer to the colander with the potatoes, run under cold water and pat dry.

3.  Mix the mayo, sour cream, mustard, tarragon, lemon juice and zest, 1/2 tsp salt and pepper to taste in a bowl.  Add the potatoes, green beans, and onion; season with salt and pepper, and toss.  (I usually let it sit in the fridge for a couple hours before serving)