Set a rack in the center of the oven and heat the oven to 450°F.: The oven screaming to temperature creates immediate dry heat that encourages the skin to brown and crisp, producing audible crackles as fat renders; you will smell the faint toasty warmth of the oven as it stabilizes. Preheating is crucial, because placing the hens into a cold oven will lengthen cooking time and prevent a quick skin sear, which can lead to soggy skin. One common misstep is not allowing the oven enough time to fully preheat, which makes the initial roasting ineffective.
With a sharp knife or poultry shears, remove the backbones from the hens and slice through the breastbone, cutting the hens in half.: When you cut the birds, the room fills with a clean, meaty scent and you can see the structure of the breast and thigh, which allows more even roasting. Spatchcocking or halving increases surface area so the skin crisps and the meat cooks faster and more uniformly, ensuring tender dark meat without drying the breast. Avoid dull blades that tear the skin rather than cut cleanly, which can make presentation messy and affect even cooking.
Brush the skin of the hens with 2 teaspoons of the sesame oil and set them, skin-side-up, on a wire rack set in a rimmed baking sheet. Sprinkle the skin with 1/2 teaspoon salt and several grinds of pepper.: The sesame oil gives a glossy sheen and a toasty aroma as it heats, and the rack lets air circulate so fat drips away and the underside is not steamed. Salt on the skin draws out a little moisture then encourages browning and crisping, while pepper gives a background bite. A frequent error is placing hens directly on the pan without a rack which leads to pooling fat and less crisp skin.
Roast until the hens are almost cooked through (an instant-read thermometer inserted into the thickest part of the thigh should register 165°F), about 25 minutes.: During this roast you will notice the skin changing from pale to golden then deeper brown, and the kitchen will fill with roasted, slightly sweet aromas. Hitting the temperature target ensures safe, juicy meat; pulling too early leaves connective tissues undercooked, while over roasting dries the breast. One troubleshooting tip is to rotate the pan halfway through if your oven has hot spots, preventing uneven browning.
Heat 2 teaspoons of sesame oil in a small saucepan over medium heat. Add the ginger and garlic and cook, stirring often, until soft and fragrant, 2 to 3 minutes. Stir in the preserves/jam, honey, soy sauce, and lemon juice; bring to a boil and cook, stirring occasionally, until the mixture has thickened slightly, 4 to 5 minutes. Dissolve the cornstarch in 1 teaspoon of water, add to the saucepan, and cook until the mixture thickens, another 1 minute.: As you cook the aromatics the pan will perfume the kitchen with sharp, warming ginger and toasted garlic , then the jam will melt and bubble into a glossy syrup; you can hear a steady light simmer and see the texture change from runny to syrupy. Thickening concentrates flavors and lets the glaze cling to skin, which creates that lacquered finish. Avoid cooking on too high heat, which can burn the sugars and make the glaze bitter; if it begins to darken too quickly, lower the heat and stir more often.
Brush the hens with the apricot ginger glaze and continue to roast until the glaze has browned in spots and the thermometer registers 170°F in the thigh, another 5 to 7 minutes.: When you lacquer the hens the aroma shifts to bright fruit and warm spice, and the glaze will begin to bubble and caramelize at the edges, creating glossy browned spots that catch the light. The final few minutes allow the glaze to set and the internal temperature to reach the safe target, which also helps the meat relax and reabsorb juices. A common mistake is brushing too many coats too early which can lead to burnt sugar; instead apply one good layer and finish in the oven, watching closely.
Season with salt and pepper, and serve immediately.: At the finish you will notice the skin crackle slightly when you move the hens and the glaze will be tacky and fragrant, with a balance of sweet, tart, and savory notes. Resting is minimal here because these small birds cool quickly, so season subtly to taste and plate while the skin remains appealingly crisp. One misstep is letting the finished hens sit too long uncovered, which causes the glaze to lose its glossy appeal and the skin to soften.