In a large bowl, combine the water, salt, and 1½ teaspoons oil. Slowly add the masarepa and mix with your hands until a smooth, homogeneous dough forms. Let the dough rest for 10 minutes. Don’t worry if the dough is too soft at first; the flour will hydrate as it rests to become smooth and malleable.
Divide the dough into 4 balls, then shape into patties. Press herbs and flowers onto both sides of each patty.
Heat a large pan over medium heat. Add a small drizzle of oil and use a paper towel to distribute in an even layer over the surface of the pan. Too much oil will prevent the arepas from caramelizing. Add the patties to the pan and sear for 4 minutes on each side, until starting to puff up and turn golden brown in spots.
Set the arepas on a baking sheet, then transfer to the oven to finish cooking for about 10 minutes. You’ll know they are done when they make a hollow sound when tapped.
Cut the arepas open, fill with your desired fillings, serve immediately.