Carefully slice an avocado in half, remove the seed, and place the flesh in a bowl. Add the dehydrated onion pieces and and lemon juice and mash together. Sprinkle with sea salt. Set aside.
Slather the top of 4 slice of bread with dairy-free margarine. Place these on a skillet and turn the heat up to medium-low.
Layer over the 4 slices of bread thin slices of the cheese, one to two slices of the tofurkey, and the avocado mixture.
Slather margarine on top of the 4 remaining slices of bread. Place the unbuttered side down on the four sandwich bottoms cooking in the skillet.
Spread the jalapeño slices in bare spots on the skillet so they can cook along side the sandwiches. Tip: Be sure to wear gloves or wash your hands after handling jalapeños.
Once the bottoms have turned golden brown, carefully turn the sandwiches over so the buttered side of the top slice of bread is now on the skillet. Cook for another couple of minutes until that slice is golden brown as well, and the cheese is slightly melted.
Serve sandwiches warm with slices of grilled jalapeño on top as a garnish or on the side. Once the seeds are removed and they're grilled a bit, jalapeños will provide lots of flavor without all that heat.