Place the cut apples in a large bowl and cover with cold water. Add the lemon juice and keep the apples submerged while preparing the batter. The lemon water prevents the cut surfaces from browning.
4 small Granny Smith apples, cold water, 2 tbsps (30 ml) fresh lemon juice
Whisk the flour, cornstarch and salt together in a large bowl. Add the ice-cold water and whisk until combined. The batter should be fluid enough to coat the apples easily while still leaving a visible layer on the surface.
¼ cup (32 g) cornstarch, ¾ cup (90 g) all-purpose flour, ⅔ cup (160 ml) ice-cold water, ½ tsp (1.5 g) kosher salt
Preheat the oven to its lowest setting. Pour the canola oil into a Dutch oven or wok and heat over medium heat to 350°F (177°C). Set a wire rack over a rimmed baking sheet.
6 cups (1.4 L) canola oil
Drain the apples and pat them very dry with paper towels. Transfer to a clean bowl, add the cornstarch and toss until every piece has a thin, even coating.
¼ cup (32 g) cornstarch
Add about one-third of the apples to the batter. Lift out one piece at a time, allow the excess batter to drip back into the bowl, then carefully lower it into the 350°F (177°C) oil. Fry for 4 to 5 minutes, turning occasionally, until the coating is set and pale golden. Do not crowd the pot.
Transfer the fried apples to the wire rack. Allow the oil to return to 350°F (177°C), then batter and fry the remaining apples in two more batches.
Increase the oil temperature to 375°F (191°C). Fry the apples a second time in batches for 45 to 60 seconds, until the coating is crisp and golden. Transfer to the wire rack, then place the baking sheet in the warm oven while preparing the caramel.
Lightly grease a serving platter with sesame oil or neutral oil. Fill a wide serving bowl with cold water and ice. Place the platter, ice water, warm fried apples and two heatproof spatulas within reach of the stove before making the caramel. Once the caramel reaches temperature, work without pausing.
1 tsp (5 ml) sesame oil, cold water, ice
Combine the sugar, water and light corn syrup in a large nonstick skillet. Stir gently until the sugar is evenly moistened.
1¼ cups (250 g) granulated sugar, ⅓ cup (80 ml) water, 2 tbsps (40 g) light corn syrup
Place the skillet over medium heat and bring the sugar mixture to a gentle boil. Once boiling, do not stir. Cook, gently swirling the skillet only when needed, until the caramel reaches 300–305°F (149–152°C) and is pale golden.
Remove the skillet from the heat and immediately stir in the toasted sesame seeds.
1 tbsp (9 g) toasted sesame seeds
Immediately add half of the warm fried apples to the caramel. Using two heatproof spatulas, toss quickly until the pieces have a thin, even coating of caramel. Transfer immediately to the greased platter.
Add the remaining fried apples and quickly coat them in the remaining caramel. If the caramel becomes too firm to coat the apples, return the skillet to very low heat for a few seconds, only until it becomes fluid again, then immediately remove it from the heat. Transfer the coated apples to the platter.
Serve immediately with the bowl of ice water alongside. Using chopsticks or tongs, dip one caramel-coated apple piece into the ice water for 1 to 2 seconds. The ice water rapidly cools and sets the hot caramel into a thin, brittle shell. Allow the excess water to drip off before eating. Repeat with each piece as it is eaten.