Step 1: Preheat the oven - Set your oven to 400°F or 200°C. Give it a few minutes to fully heat up while you get everything else ready.
Step 2: Make the sauce base - In a small bowl, mix together the soy sauce, lemon juice, honey, mustard, minced garlic, and black pepper. Stir until everything is well combined and smooth.
Step 3: Thicken the sauce - In another small bowl, dissolve the cornstarch in the water. Make sure it is fully mixed so there are no lumps. Add this to your sauce mixture and whisk until it is completely smooth.
Step 4: Prepare the chicken - Place the chicken thighs in a casserole dish. Leave a little space between each piece so they cook evenly. Arrange them skin side down to start.
Step 5: Add the sauce - Pour the sauce over the chicken, making sure each piece is well coated. Do not worry if it looks a bit thin at this stage. It will thicken as it bakes.
Step 6: First bake - Place the dish in the oven and bake for 20 minutes. This gives the chicken time to start cooking and absorbing all those flavors.
Step 7: Flip and baste - Carefully remove the dish from the oven. Turn the chicken thighs skin side up and spoon some of the sauce over the top of each piece.
Step 8: Final bake - Return the dish to the oven and bake for another 20 minutes. The chicken should be fully cooked, golden brown, and beautifully glazed.
Step 9: Rest and serve - Take the chicken out of the oven and let it rest for about 5 minutes. This helps keep it juicy. Garnish with chopped chives and sesame seeds before serving.