Using the tip of a knife, score the surface of the squid in a crisscross pattern to prevent it from over-curling during cooking. Bring a saucepan of water to a boil and poach the squid until it just begins to curl, 2–3 minutes. Remove from the heat, drain and slice the squid into ¾ x 2½-in (2 x 6-cm) strips. Slice the bell pepper into strips roughly the same size.