Cut the peppers in half lengthways through the stalks, scrape out the seeds and trim away any white pith inside.
Boil the orzo in salted water for a half the recommended cooking time (if it suggests, say, 10 minutes, cook it for only five), then drain well.
Working in a frying pan, warm a few tablespoons of olive oil and a bit of butter, then fry the onion and garlic until soft.
Add the par-cooked orzo, parsley, tomato, tuna, capers and anchovies, then taste and season with salt as needed (it probably won’t need much) and generously with black pepper.
Fill the pepper boats almost to the brim with the orzo mixture and arrange them snugly in a suitable baking tray.
Spoon three tablespoons of water and three tablespoons of oil into the bottom of the tray, cover loosely but completely with foil, and bake for 40 minutes, removing the foil for the last 10 minutes.
Before serving, finish by zigzagging each pepper with a bit of olive oil, or spooning over some melted butter and anchovies, or thinning some basil pesto with extra-virgin olive oil, spooning that over the peppers and topping each half-pepper with a basil leaf.
