Place the sardines in a shallow baking dish or tray.
On a cutting board, crush and mince the garlic cloves. Rinse the cilantro under cool water, shake off any excess water then lay it on the board, roughly chop it and mix with the garlic. Push the mixture to the side.
Cut the piri piri pepper lengthwise and scrape out the white membrane and seeds with the point of the knife, careful not to touch them with bare hands. Julienne the peppers into thin strips.
Open the sardines and stuff each with the garlic and cilantro mixture along with the piri piri peppers, reserving some of the mixture for the outside of the sardines.
Drizzle olive oil on top of the sardines, season with salt and the garlic/cilantro/piri piri peppers, cut the lemon in half and squeeze the juice on top. Turn the sardines over and repeat with the other side. Cover and allow the sardines to absorb the flavors while preparing the grill.
Prepare the grill grate by oiling it before lighting the charcoal or a gas grill to create high direct heat. If using charcoal, it may take anywhere from 15-30 minutes before the coals are hot enough to cook the sardines over.
Remove the cover from the sardines and lay them on the grill once it’s very hot. Allow the sardines to cook and char on both sides; approximately 2-4 minutes each side. Transfer the cooked sardines to a plate with a metal spatula or tongs and cover loosely with tin foil to keep them from getting too cool.
Drizzle a little oil on one side of the bread and lay it, oil side down on the grill. Grill 2 minutes or until char marks form on the bread and remove.
Lay the cooked sardines on the grilled bread slices and serve immediately.