Gently drain the canned sardines into a fine sieve with a bowl underneath

Add the flour into a bowl, crack the egg into a separate bowl, add in the milk, and season with salt & pepper, whisk togteher, add the panko breadcrumbs into a third separate bowl

Heat a medium-sized fry pan with a medium heat and add in the virgin olive oil

While the oil is heating, gently coat each sardine, first in the flour, then in the egg wash, and finally in the panko breadcrumbs

Once the oil is nice and hot, add in the breaded sardines, all in a single layer and evenly spaced out, fry for 2 minutes per side or until golden and crispy, then transfer into a dish with paper towels

While the sardines are slightly cooling, add the mayonnaise into a bowl, along with the Dijon mustard, grated garlic, lemon juice, and olive oil, then season with salt & pepper and whisk together until you get a creamy sauce

Cut the baguette into 3-inch (8 cm) pieces, then slice each piece open lengthwise for the sandwich filling

Spread some of the mayo aioli over the bottom and top slice of the sandwich, then add in 2 sardines over the bottom slice, and top off with 2 slices of tomato and some chopped lettuce, serve at once, enjoy!