In the bowl of a stand mixer combine 2 cups flour, ½ tsp salt, and ½ tsp sugar. Use a spoon to mix. Add the 1 ½ tsp instant yeast and mix to combine again.
Heat the 1 cup milk up to 120 degrees Fahrenheit (or the temperature listed on your package instructions). Then add the milk into the flour bowl. Stir with a spoon again to combine.
Add the dough hook onto the stand mixer and knead the dough on a low speed for about 2 minutes. Once the dough starts to stick to the side of the bowl, add the 1 tsp vegetable oil. Knead for another minute or so.
Add 1 tbsp of flour and continue kneading until the dough begins to pull away from the sides of the bowl. Once the dough begins to pull away from the side of the bowl, turn off the mixer. The entire kneading process should take about 5 minutes. The dough should have a lot of elasticity but will still stick to your fingers a bit.
Use nonstick spray to grease a large mixing bowl. Then add the dough into the bowl. Cover it with a kitchen towel and allow it to rest in a warm, dark place for about an hour or until it doubles in size (see notes below for Instant Pot instructions).
While the dough is rising, add the ½ cup olive oil and 5 cloves garlic cloves together into an airtight container. Set aside.
Once risen, remove the dough from the bowl and turn it out onto a floured surface. Use a knife to cut the dough into 4 equal pieces, rolling each quarter into a ball.
Use your hands to press the dough into a circle shape, leaving the edges a little thicker than the center. Cut a slit into the center of each langos.
Heat some oil in a pot/pan to 350 degrees Fahrenheit. Add the langos one at a time, frying until browned on each side (about 1-2 minutes each). Remove to a paper towel-lined plate.
Use a pastry brush to brush each langos with garlic-infused olive oil. Then spread sour cream onto each langos, and top with shredded cheese. Serve warm. Enjoy!