In a large mixing bowl, dissolve the yeast in warm water with 1 tablespoon of honey. Let it stand for 5-10 minutes until foamy.
Add the remaining honey, oil, eggs, and salt to the yeast mixture, whisking until well combined.
Gradually add 3½ cups of flour, mixing until the dough begins to pull away from the sides of the bowl. The dough should feel tacky but not sticky—if it's too sticky, add the remaining flour a tablespoon at a time.
Turn the dough onto a lightly floured surface and knead for 8-10 minutes until smooth and elastic.
Place the dough in an oiled bowl, turning to coat. Cover with a damp cloth and let rise in a warm place for about 1 hour or until doubled in size.
While the dough rises, combine the diced apple, brown sugar, cinnamon, and lemon juice in a small bowl for the filling.
Once risen, divide the dough into three equal portions. Roll each portion into a 14-inch rope, then flatten each rope into a rectangle.
Sprinkle the apple filling evenly down the center of each rectangle, leaving a half-inch border.
Fold the long edges of each rectangle over the filling, pinching to seal. Gently roll each filled piece back into a rope, taking care not to squeeze out the filling.
Arrange the three ropes side by side, pinching them together at the top. Braid the ropes, tucking the ends under when finished.
Transfer the braided loaf to a parchment-lined baking sheet. Cover loosely and let rise for about 40 minutes, until puffy but not quite doubled.
Preheat oven to 350°F. Gently brush the challah with egg wash, making sure to get into all the crevices.
Warm the honey slightly and brush it over the egg wash. If using, sprinkle with sliced almonds.
Bake for 35-40 minutes until deeply golden brown. If the bread begins to brown too quickly, tent loosely with foil. The internal temperature should reach 190°F when fully baked.
Allow the bread to cool on a wire rack for at least 30 minutes before slicing.