Place Red Bell Pepper (2) and Beefsteak Tomato (2) in a medium-sized saucepan or pot. Pour in Water (1/2 cup) and turn heat to high. Season with Kosher Salt and Freshly Ground Black Pepper (1 teaspoon). Bring to a simmer, then turn heat down to medium high. Set a timer for 25 minutes.
After about 5 minutes, the tomatoes and peppers will begin to release their juices, and the whole mixture should be bubbling. Adjust the heat if necessary so that the mixture stays at a constant bubble. Stir every 5 minutes or so to make sure the tomatoes and peppers are not sticking to the bottom of the pan. If they are, add water by the 1/4 cup.
When the peppers and tomatoes are tender and nearly all of the liquid has evaporated and the tomatoes and peppers are beginning to stick to pot, add the Fresh Basil Leaf (1/4 cup), Butter (2 tablespoon) and Olive Oil (2 tablespoon) to the pot, give it a stir, then transfer the contents of the pot to a food processor or blender. Blend until smooth. Taste. Adjust seasoning with more salt and pepper as necessary.
Serve sauce with Pasta Shells (to taste).