Reserve 2 Tbs. of the butter, and melt the rest in a saucepan. Ad the flour and cook over medium-low heat, as if making a roux, stirring constantly, until the texture changes. Do not allow it to brown.
Add the milk and whisk until well blended into what looks like thin mashed potatoes. This is a bechamel. Remove from heat.
Combine crabmeat, tasso, bell pepper, and green onions. Add this to the bechamel, and stir in gently with a wooden spoon.
Turn the mixture out onto a cutting board. Form round, flat cakes the size of thick hamburgers.
Put the bread crumbs onto a plate and gently press the crab patties down to coat.
Heat the remaining butter to bubbling in a skillet over medium-high heat. Cook the crab cakes on both sides until a crusty brown.
Combine all the ingredients for the white remoulade.
Warm the bread rolls in the oven. Spread with the remoulade and place a crab cake in each. Baby lettuce makes a nice finishing touch, if you like.