Spinach-Sorrel Tarts

INGREDIENTS

2 1/2 cups

all-purpose flour

1 tsp

sugar

1 tsp

coarse salt

1 1/2 tsp

coarsely ground pepper

1 stick

cold unsalted butter, cut into small pieces

1/4

to 1/2 cup ice water

1/4 cup

extra-virgin olive oil

3 1/2 cups

thinly sliced onions (1 pound)

1 1/2 tbsp

minced garlic (4 cloves)

red-pepper flakes

1/2 lb

spinach, stems removed

1/2 lb

sorrel

All-purpose flour, for rolling

Coarse salt

to 8 ounces Morbier cheese, rind removed and sliced lengthwise into long pieces