Bánh coóc mò (Tày pointed sticky-rice packets)

Sort and rinse the black beans. Cover with plenty of cool water and soak for 8 hours or overnight in the refrigerator. Drain. Rinse the glutinous rice until the water is mostly clear, cover with cool water and soak for 3 hours at room temperature; drain thoroughly.

Wash the banana leaves under running water and wipe dry. Pass each piece briefly over low heat or dip it in hot water just until pliable; do not scorch. Cut pieces large enough to form long pointed cones with overlapping seams.

Mix the drained rice, drained beans and salt. Divide into 8 portions. Form each into a compact elongated cone inside a leaf, leaving a little room for expansion. Fold and overlap the leaf securely, then tie firmly with twine. Check that no rice can escape.

Arrange the packets snugly in a large stockpot and cover with at least 5 cm water. Bring to a full boil over high heat, then reduce just enough to maintain a steady boil. Cover and cook for 2 hours 30 minutes, checking occasionally and topping up with boiling water so packets stay submerged. The rice should be uniformly tender without a hard or chalky center; if needed, boil in 15-minute increments.

Turn off the heat and let the packets stand in the hot water for 10 minutes. Lift them out with tongs and drain on a clean rack. Rest for 10 minutes before untying so the rice can settle.

Serve warm or at room temperature, plain or with sesame-peanut salt on the side. Keep each pointed packet intact until serving; unwrap and slice or eat by hand.

Serve promptly. Keep hot packets at 60°C / 140°F or hotter if holding. Cool leftovers promptly and refrigerate within 2 hours (within 1 hour above 32°C / 90°F); store at or below 4°C / 40°F for up to 3 days. Reheat until steaming throughout and at least 74°C / 165°F in the center.