To make the salsa: Combine the herbs, capers, garlic, lemon zest and juice in the bowl of a processor. Process until coarsely chopped, scraping the bowl as necessary.
Add the olive oil and process until finely chopped, scraping bowl as necessary. If mixture is too thick add water a little at a time until the consistency is as you like it. Pour the salsa into a container cover and refrigerate until ready to use.
Grill or broil the sausages. Allow to cool enough to slice thinly. Combine the sausage slices and the marinara sauce in a saucepan. Simmer for 5-7 minutes.
While the sausage simmers, saute the the onions and peppers in the olive oil. They should be lightly browned but still crunchy.
Assemble the Tacos: Divide the sausage between the tortillas. Top the sausage with the peppers and onions. Add the tomato slices. Drizzle with the Salsa Verde and sprinkle with the cheese.