1. Adjust an oven rack to the top position and heat the broiler to high. Place the red pepper on a baking sheet and cook until charred on all sides, using tongs to turn it often, about 8 minutes total. Remove the pepper from the oven and set aside until cool enough to handle, about 15 minutes.

2. Place the pepper in a fine-mesh sieve set over a blender jar. Open the pepper with a knife (the blender jar will catch the juices) and remove and discard the seeds. Add the roasted pepper and its charred skin to the blender along with the tomato purée, orange juice, Worcestershire, olive oil, balsamic vinegar, molasses, salt, mustard, ginger, pepper, onion powder and allspice and blend until smooth.

3. In a small saucepan set over medium heat, add the sauce and cook until bubbles start to break on the surface, 5 to 10 minutes. Cool and serve alongside the steak. (For a very smooth consistency, strain the sauce before serving.)