Toss potatoes with olive oil. Bake potato slices on a baking sheet for about 15 minutes, turn over and bake another 15 - 20 minutes until golden and slightly crisp.
Next, in a single layer overlap the potatoes in a cast-iron skillet that can be baked in the oven. Season potatoes with salt and pepper. Sprinkle with cheese and bacon. Bake for 5 minutes to melt cheese. Then sprinkle with scallions and cilantro.
For dip: In a separate dish, stir diced tomatoes into the sour cream. Serve on the side as a dip.
If you don't have an oven-safe cast-iron skillet, you can use another oven safe dish like a pie plate or casserole dish.
You can go with a Mexican pre-grated cheese, but I recommend aged cheese that you grate yourself. The pre-grated type contains preservatives meant to keep it from clumping. It doesn’t melt quite as well.