Melt the butter in the skillet. Add the onion and cook over moderate heat, stirring, until softened, about 5 minutes. Add the Peppadews and jalapeños and cook, stirring, for 1 minute. Add the broth and coffee and cook until reduced by half, scraping up any bits stuck to the bottom of the skillet, about 5 minutes. Whisk in the cornstarch slurry and cook until the gravy is thickened, about 1 minute. Season with salt and black pepper. Slice the ham steak into four pieces, pour the gravy on top and serve.