Mix the mayo, tuna, shallot, garlic, lemon juice, and salt in a bowl.
Toast your bread on one side.
Top the toasted side with tuna salad, a handful of grated cheddar, and jalapeño slices.
Broil the sandwich(es) until the cheese is fully melted.
Serve right away.
Alternative
**If you want to take the homemade mayonnaise route: start with 1 egg yolk, 1 tsp mustard, salt, then drizzle enough oil in until you have ⅓ cup mayo
