1poundsmall potatoes(red or gold potatoes work well)
1teaspoonspicy brown mustard(or Dijon)
salt, to taste
water, as needed
To cook the potatoes, fill a saucepan with an inch of water and arrange a steamer basket over that. Add the whole potatoes into the steamer basket, and bring the water to a boil. Once boiling, lower the heat and cover the pot with a lid, letting the potatoes steam until fork tender, about 15 to 20 minutes. (Time-saving tip: You can cut the potatoes in half before you cook them, to speed the cooking process!)
Once cooked, transfer the potatoes to a bowl of ice water to help them cool quickly. Once they are cool enough to handle, slice them in half (if you haven't already) and use a spoon to scoop some of the centers out. Make sure you leave enough potato around the edge of the shell so that they are sturdy enough to be hand-held later. (Leave about 1/4-inch of potato all the way around the shell.)
Add the scooped-out potato to a medium bowl, and add in the hummus, mustard, 1/4 teaspoon of salt, and a tablespoon of water. Use a fork to mash it all together, until a relatively smooth filling is formed. Add another tablespoon or two of water, as needed to maket the filling smooth and fluffy, similar to a deviled egg filling. Taste the mixture and add more salt, mustard, or hummus, to taste. You can also add a splash of lemon juice or pickle juice for a more tangy flavor.
Transfer the filling to a piping bag fitted with the largest piping tip that you have. (Or use a plastic sandwich bag with one of the bottom corners cut-off for a piping tip.) Squeeze the filling into the reserved potato shells, as if you're filling a deviled egg.
Garnish with paprika and chopped chives, if desired. Serve right away at room temperature, or you can serve them chilled or warm. To reheat, place them on a pan and warm them in the oven at 350ºF for 10 minutes. Leftovers can be stored in an airtight container in the fridge for up to 5 days.