The Secret to the Golden Crunch
According to Chef Mateo, the secret is all in the mayonnaise crust. By spreading a thin layer of mayonnaise on the outside of the sourdough instead of just butter, you achieve an extra level of golden crispiness that stands up to the rich, melty fillings inside.
Step 1: Caramelize the onions
Start by thinly slicing your onions. In a small pot, melt about an ounce of butter with a splash of oil. Toss in the onions along with salt, pepper, a bay leaf, and a sprig of fresh thyme. Cook them slowly until they turn a deep, juicy golden brown. If the pan starts to get too dark on the sides, pour in a little water to deglaze it. This "cleans" the pot and pulls all that incredible caramelized flavor back into the onions. Once they are sweet and brown, remove the herbs and set the onions aside to cool.
Step 2: Prep the bacon and tomatoes
In a teflon pan over medium heat, lightly sear your applewood pork bacon. Chef Mateo suggests not making it too crispy at this stage; you just want to render some of the fat and extract that smoky flavor. Remove the bacon and, in that same pan with the leftover bacon fat, sear thick slices of tomato. Season them with a little pepper and dried oregano. You only need to cook them until they start to char slightly on the edges.
Step 3: Butterfly the shrimp
For this sandwich, use cooked prawns with the tails removed. A great professional tip is to butterfly the shrimp by slicing them in half lengthwise. This makes the shrimp thinner, which ensures they stay put inside the sandwich and makes the whole "beast" much easier to bite into.
Step 4: Build the sandwich
Now it is time for the assembly. Take two thick slices of sourdough and spread a generous layer of your caramelized onions on the bottom piece. Add a slice of cheese, followed by the seared tomatoes, the bacon, and a layer of the butterflied shrimp. Top it off with another slice of cheese to ensure everything is glued together. Close the sandwich and spread a thin layer of mayonnaise on both of the outward-facing sides of the bread.
Step 5: The final sear
Heat a clean pan over low fire with a mix of oil and butter. Once the butter starts to fry, place the sandwich in and press it down slightly with a spatula. Cook for a few minutes on each side. The goal is a low, slow heat that melts the cheese completely while turning the mayonnaise-coated sourdough into a perfectly crispy, golden brown crust.
How to Serve
Slice the sandwich in half diagonally to show off those beautiful layers of pink shrimp, red tomato, and melty cheese. This is a heavy, satisfying meal that pairs perfectly with a simple side of greens or just a hot cup of coffee. It is a bold, indulgent way to start your day that feels like a true reward.
The result is a sandwich that is smoky, sweet, and incredibly crunchy. As Chef Mateo says, when that cheese melts into the shrimp and bacon, it creates a flavor that is simply incredible.
Watch the "Beast" Being Made
Want to see the exact color those onions should be or how Chef Mateo deglazes his pan to capture every bit of flavor? Watch the full episode of Seafood Everyday to see this indulgent grilled cheese come to life.
