In a small bowl, combine the cream cheese and bagel seasoning. Mix well until smooth and creamy.
Using your knife, slice the cucumbers, red onion, radishes, and jalapeno (if using) into thin pieces. Set aside.
If you prefer a bit of crunch, lightly toast your sandwich bread until golden brown.
Spread a generous layer of the cream cheese mixture on one side of each slice of bread. On two of the slices, layer the arugula, followed by the sliced cucumbers, red onions, and radishes.
Carefully layer the smoked salmon on top of the veggies. Add the sliced avocados and sprinkle with chili flakes for a hint of heat, if desired.
Top with the remaining slices of bread, cream cheese side down, and cut the sandwiches in half. Serve immediately, or wrap them up for a delightful lunch on the go.