Melt 1 TBSP butter in a small pot over medium-high heat. Add half the sesame seeds and toast, stirring constantly, until fragrant and light golden, 30 seconds to 1 minute. Stir in rice, 1¼ cups water, and a pinch of salt. Bring to a boil, then cover, lower heat, and reduce to a gentle simmer. Cook until tender, about 15 minutes. Keep covered off heat until meal is ready.