Combine water and ube flavoring (or 1 teaspoon violet food coloring). Slowly add to the flour and mix well (using clean hands) until it forms a dough. Pass through the holes of a fine grater. If your dough is too dry, add more water, 1 tablespoon at a time until the dough comes together.
Prepare foil pieces and brush with oil. Gently place about 3 heaping tablespoons of grated dough on the prepared foil. Form into a long log. Do not pack for faster and even cooking.
Pick it up as you would a taco. Fold and pinch the edges (log ends) to seal but leave the top open. When done, arrange in a steamer, leaving a bit of space between pieces to give room for the steam to evenly cook the puto bumbong.
Steam for 15 minutes or until cooked through. Transfer to a clean banana leaf and brush generously with softened butter. Top with grated coconut and sugar. Alternatively, you can use grated cheese and condensed milk. Serve hot.