First things first—prepare your ingredients. If you're making a bite-sized appetizer, go for a finer, smaller chop. If you're making a sharing plate, your chop can be a little rougher.
Cut the avocado in cubes. Set aside.
Slice the green onion, both white & green parts. Set aside.
Finely chop the jalapeno. Avoid the seeds. Set aside.
Cut the tuna into very small cubes. Start by thinly slicing along the length of the lines, and proceed to cut into cubes. Set aside.
Make the sauce
Stir together the olive oil, soy sauce, tabasco, lime juice and salt & pepper in a small bowl. Mix well to blend. Adjust to your taste. You can add more tabasco for more kick, more lime for more citrus, more olive oil for more dilution.
Bring it together
Option 1: Classic tartare — Mix the tuna, avocado, onion & jalapeno with the sauce, stirring just to combine. Be gentle when mixing to prevent ingredients (i.e. avocado) from getting messy.
Option 2: Sharing plate — A trendier take on the dish, start by placing the tuna cubes in the center of a large plate. Then, top with avocado, green onion and jalapeno, in that order. Pour sauce on top just before serving.
Option 3: Appetizer bites — Follow the same instructions as #2 (i.e. mix all together), and then separate into individual serving spoons, mini appetizer bowls / plates or toasted pitas for some crunch.
Optional
Serve alongside toasted pita slices, baguette crisps or tortilla chips.