To make the
tart shell, mix together the yeast, 1 cup water, flour, and a pinch of
salt until well combined. Form the dough into a ball, cover with plastic
wrap, and place in the refrigerator for 3 hours. Mince the
yellow onion, garlic and fennel and place in a medium-sized saucepan.
Add 2 cups water, thyme, 1/2 tsp salt, and 1 tbsp sugar. Cook over
medium heat for 25 minutes, or until all the water has been cooked away.
Cool to room temperature.
fennel-onion marmalade is cooking, place the pearl onions, remaining 1
cup water, 1/2 tsp salt, 1 tsp sugar, balsamic vinegar into a saucepan.
Cook over medium-low heat for 20 minutes, or until the water is
completely reduced and onions are tender. Cool to room temperature. Preheat the
oven to 350 degrees. To assemble
the tart, roll the dough out to a circle about 8 inches in diameter and
place on a baking sheet. Spread the fennel-onion marmalade over the
pastry to within 1/2 inch of the edge. Top with pearl onions. Bake for
35-40 minutes, or until the pastry is golden brown and cooked through.
Remove from the oven and garnish with chives. Cut into 4-6 wedges and
serve warm or at room temperature.