In a small bowl combine the yeast and warm water. Set aside.
In a small saucepan heat the milk until it is scalded (reaches 180 degrees F). In a large bowl combine the scalded milk, sugar, salt, cinnamon, & raisins. Let it cool for 5 minutes (until it is lukewarm). Add the yeast mixture & eggs and stir until combined.
Sift the flour onto a piece of wax or parchment paper. Measure 2 cups of the sifted flour and add it to the yeast/raisin mixture. Stir in the melted butter. Gradually add in the remaining 2 cups sifted flour and gently stir to combine. (The dough will be very sticky at this point.)
Grease a medium-sized bowl with the vegetable oil. Add the dough to the greased bowl. Pour a little bit of oil onto the dough and use a paper towel to coat the entire top. Place a piece of wax or parchment paper over the top of the dough and refrigerate for 10 minutes (this will make the dough easier to handle).
Turn the rested dough out onto a piece of wax or parchment paper. Use a knife to cut the dough into 12 equal portions.
Grease a cookie sheet with a bit of vegetable oil. Shape each of the 12 portions into a ball and place on the cookie sheet. Cover with a clean kitchen towel and put in a warm place to let rise for 1 hour.
Preheat the oven to 400 degrees.
Remove the kitchen towel from the cookie sheet. Bake the hot cross buns for 12 minutes. Let cool on the cookie sheet for a minute after removing from the oven, then finish cooling on a rack.
Prepare the powdered sugar frosting (see below) and mark each bun with a cross of frosting.
Powdered Sugar Frosting
Combine all the ingredients in a small bowl. If the mixture is too thick to spread easily, add a little more milk.