For the French toast

3 large eggs

1 cup whole milk

1 teaspoon sugar

1/4 teaspoon salt

1 (1-lb) challah loaf, cut crosswise into 12 (1/2-inch-thick) slices (not including end pieces)

3 1/2 tablespoons unsalted butter

For berry sauce

3 cups mixed berries such as blackberries, raspberries, and blueberries

1/3 to 1/2 cup sugar (depending on sweetness of berries)

1 tablespoon fresh lemon juice

Garnish:

confectioners sugar for dusting