In a large bowl, whisk together the flour, instant yeast, granulated sugar, salt, and ground cinnamon.

In a separate bowl or measuring jug, combine the warm milk, egg, vanilla extract, and 2 tbsp oil or melted butter; whisk until smooth.

Pour the wet ingredients into the dry ingredients and whisk or stir until you have a thick, smooth batter with no dry pockets. The batter should be thicker than regular pancake batter but still pourable; if it seems too stiff, add 1–2 tbsp more milk.

Cover the bowl with a clean kitchen towel or plastic wrap and let the batter rise in a warm place until puffy and roughly doubled in volume, about 40–60 minutes.

While the batter is rising, peel, core, and dice the apples into small cubes (about 1/4 inch). Toss with lemon zest if using and set aside.

When the batter has risen, gently fold the diced apples into it with a spatula, distributing them evenly without knocking out all the air.

Heat a large nonstick or heavy skillet over medium heat. Add enough neutral oil to lightly coat the bottom of the pan (about 2–3 tbsp) and heat until shimmering but not smoking.

Using a spoon or small ladle, drop portions of batter into the hot pan, making rounds about 3 inches wide. Do not overcrowd the pan; leave space between racuchy.

Fry each racuchy for 3–4 minutes on the first side, until the edges look set and the underside is deep golden brown. Adjust the heat as needed so they brown steadily without burning.

Flip carefully and fry another 3–4 minutes on the second side, until golden brown and the center feels springy when gently pressed. If they brown too fast while staying raw inside, lower the heat slightly.

Transfer cooked racuchy to a plate lined with paper towels to drain excess oil. Keep warm in a low oven (about 200°F) while you cook the remaining batches, adding a little more oil to the pan as needed.

Serve warm, dusted generously with powdered sugar. You can also serve with applesauce or a dollop of sour cream if desired.