You can use regular cucumbers, but I prefer either a pickling cucumber or English cucumbers.
1 quart apple cider vinegar
2 quarts water
1/4 cup kosher salt
2 sprigs fresh dill
1/4 teaspoon red pepper flakes
3 cloves garlic, smashed but not chopped
Combine apple cider vinegar, water and salt. Bring to a boil, just until salt dissolves.
In the meantime, cut cucumbers into wedges.
In a large container, place dill, garlic and red pepper flakes. Place cucumber wedges into the container.
Once vinegar solution has come to a boil, pour over cucumbers. Stash the container in the fridge. My kids will eat these almost immediately, but they're better once they've chilled, and even better after a couple of days!