Preheat oven to 200°F.
Heat 1 Tablespoon olive oil in a skillet over medium heat.
Add onion, 1/2 teaspoon salt, and 1/8 teaspoon pepper.
Cook until onions are translucent, about 5 minutes.
Set aside.
Cut fish into large chunks; pulse in a food processor to coarsely chop.
Transfer to a medium bowl.
Add onion, tarragon, egg and Tabasco, and combine well.
Add remaining salt and pepper.
Form eight 3 inch patties; dredge them in breadcrumbs, shaking off excess.
Heat 1 Tablespoon oil in a large skillet over medium-low heat.
Cook 4 patties until browned, about 4-5 minutes on each side.
Remove to a baking sheet, cover with foil and warm, in oven.
Wipe out skillet, return to heat and add remaining olive oil.
Cook remaining patties.
Serve immediately.