Cut the tofu. Pat dry with a paper towel, and lightly sprinkle with salt. Heat a small pan with enough oil to cover the pan. Add the tofu pieces and fry until all sides are golden brown.
Bring a large pot of water to a boil over high heat, and prepare an ice bath. Blanch the spinach, place immediately in the ice bath, then squeeze out the water. Cut into short lengths.
Cut the cucumber into thick sticks. Do not use the seedy part. Heat the pan with a little bit of oil over medium high heat. Stir fry the cucumber until softened. Lightly season with salt.
When all the other ingredients are ready, remove the rice from the rice cooker. Mix well by gently folding with a rice paddle or large spoon until evenly seasoned. Add more salt to taste.
Put a sheet of gim, shiny side down and longer side toward you. Spread rice evenly over the gim, using a rice paddle. Lay the prepared ingredients on top of the rice.
Lift the entire bottom edge with both hands and roll over the filling away from you, tucking in the filling with your fingers. Put firm pressure over the roll with the help of the bamboo mat.
Rub or brush the roll with a little bit of sesame oil for extra flavor and shiny look. Wipe the knife with a damp towel if the rice still sticks. Cut the roll into 1/2-inch thick bite sizes.