Combine all 6 Balsamic Mascarpone Spread ingredients in a small bowl and stir until well blended.
Put the English muffin halves nooks-and-crannies-side down on a hot skillet or gridde pan until lightly toasted or simply pop them in a toaster. When done (and still warm), brush the top of each muffin half with olive oil and rub them with the halved garlic clove.
Next, generously smear the Balsamic Mascarpone Spread over the garlic-rubbed sides of all 8 English muffin halves. Top 4 of the smeared halves with lettuce and thinly sliced avocado. Reserve the remaining muffin halves to be the top of each sandwich.
Lightly spray your skillet or griddle pan with non-stick cooking spray and set over medium heat. Working in batches if needed, place individual slices of the smoked salmon across the pan. Let sizzle and sear undisturbed on one side for about 1 minute (longer if you want it really crispy). Then flip and sear the other side. Once done, divide the seared salmon slices among the 4 sandwich halves and top with the reserved muffin halves. Serve warm or at room temperature.
TIP A: Mascarpone cheese is an Italian cream cheese that is probably best known for being the key ingredient in tiramisu. It resembles our American cream cheese, but is slightly sweeter and smoother. It makes for a really smooth spread for these sandwiches and the sweetness pairs well with the acidity of the balsamic vinegar and caper, jalapeño, or pickle juice. If you can't find mascarpone cheese at your local grocer (typically sold in a tub in the specialty cheese section), then Neufchâtel or cream cheese are great substitutes.
TIP B: Don't throw away that left-over caper, jalapeño, or pickle juice—it's liquid gold fo sauces, spreads, and dressings! You can't go wrong with using any of them in this spread. My favorite is jalapeño juice because I like the subtle (really subtle) kick that it adds. If you're into briny flavors, then go with caper juice. And, if you want a touch more sweet, then sweet pickle juice is just the thing.