Appetizer - Mussels with Roasted Potatoes

First course or light lunch for 4.

4 large Yukon Gold or russet baking potatoes
6 T evoo
1/2 T kosher salt
1/3 cup finely chopped shallot
3 garlic cloves, minced
Rounded 1/4 t dried hot red pepper flakes
1 cup dry white wine
3/4 cup water
2 lb mussels, scrubbed well and beards removed
3 T chopped fresh parsley

Preheat oven to 450F
Halve potatoes lenthwise and trim a 1/4" thick slice from side opposite cut side of each half to form 8 flat slabs 1/2 - 3/4" thick
Discard trimmings then coat potato slabs with 2 T oil and sprinkle with all of salt. Arrange in 1 layer in large shallow baking pan (1" deep), roast in middle of oven, turning over once halfway through, until golden brown and tender, 25-30 mins.
Shortly before potatoes are done, cook shallot, garlic, red pepper flakes in 2 T oil in deep 12" skillet over mod heat, stirring until softened, abt 3 mins. Add wine and water and bring to simmer. Add mussels and cook, covered, over mod high heat until they just open wide, checking frequently after 3 mins and transferring opened mussels to a bowl. Discard any that remain unopened after 6 minutes.
Whisk parsley and remaining 2 T oil in broth and season with s & p. Divide potatoes among 4 shallow bowls and top with mussels and broth.