Whisk flour, sugar, and salt in medium bowl to blend. Add butter and rub in with fingertips until mixture resembles coarse crumbs. Add 2 tablespoons ice water; stir until dough clumps together, adding more ice water by teaspoonfuls if dough is dry. Gather dough into ball; flatten into disk. Wrap in plastic and chill at least 2 hours. DO AHEAD: Can be made 1 day ahead. Keep chilled. Let dough soften 10 minutes at room temperature before rolling out.

Combine rhubarb and ¼ cup sugar and 1 tablespoon honey in medium bowl; let stand at least 30 minutes and up to 1 hour. Position rack in center of oven and preheat to 350°F.

Place a large sheet of parchment on work surface; sprinkle parchment with flour. Roll out dough on parchment to a 12-inch round. Transfer dough on parchment to large baking sheet. Starting in center of dough round, arrange rhubarb strips in concentric circles and slightly overlapping atop dough, leaving 1-inch plain border at edge. Gently fold dough border up over outer edge of rhubarb topping, folding and crimping dough to create decorative edge. Sprinkle a heaping tablespoon of sugar over rhubarb. Dot rhubarb with butter. Brush dough edges with beaten egg. Sprinkle edges with 1 tablespoon sugar.

Place in oven and bake galette until rhubarb is tender and juices are bubbling, about 1 hour. Cool galette at least 30 minutes. Serve with whipped cream, creme fraiche or vanilla ice cream.