1. Stem bell pepper, seed, and cut into 1/4-inch-wide strips about 3 inches long.
2. Rinse chicken, pat dry, and cut crosswise into 1/4-inch-thick slices.
3. Place a 14-inch wok or 12-inch frying pan over high heat. Measure 1 tablespoon solidified coconut milk from the top of the can and add to wok with pepper and 1/4 cup water. Stir often until pepper strips are limp, 3 to 5 minutes.
4. Add remaining coconut milk and curry paste. Stir to blend smoothly. Stir until boiling; add chicken, corn, and sugar. Reduce heat to medium; stir often until chicken is white in center of thickest part (cut to test), about 3 minutes. Add lemon juice and fish sauce to taste.
5. Scoop rice into bowls and top equally with chicken curry mixture.