Step 1

Preheat oven to 375°F. Process hazelnuts, salt, and 1 1/4 cups flour in a food processor until nuts are very finely ground; transfer to a medium bowl and set aside.

Step 2

Process butter and sugar in food processor until smooth. Add egg yolks and pulse just to combine. Add reserved hazelnut mixture and pulse just until blended. Gather into a ball, flatten into a disk, and wrap in plastic. Chill for at least 2 hours. DO AHEAD: Dough can be made 1 day ahead. Keep chilled. Let stand at room temperature for 15 minutes before rolling out.

Step 3

Mix jam, lime zest, and lime juice in a small bowl to blend; set aside.

Step 4

Roll out dough on a sheet of floured parchment paper to a 14" round about 1/8" thick, dusting dough with flour as needed to prevent sticking. Spread jam mixture over dough, leaving a 1 1/2" border. Brush beaten egg on border of dough. Using parchment paper as an aid, fold border of dough over jam, pinching together any cracks in dough. Slide parchment paper with galette onto a baking sheet. Brush top of dough with beaten egg; sprinkle with raw sugar.

Step 5

Bake galette, rotating halfway through, until crust is deep golden brown, 30-40 minutes. Run a large offset spatula or knife between tart and paper to release tart from any jam that may have bubbled out. Let cool completely on pan on a wire rack. DO AHEAD: Galette can be made 3 days ahead. Keep loosely covered at room temperature.

Step 6

Cut into wedges and serve with ice cream, if desired.