Full-back Steward offered counter-attacking poise and high-ball presence, while Van Poortvliet added impetus and influence at half-back.
Guy Porter and Marcus Smith claimed two tries apiece, while further scores from Steward and Ellis Genge, to add to a penalty try, sealed England’s dominant 52-13 victory.
Not even a first-half yellow card for Jonny May could slow down a determined England, who atoned for last weekend’s 30-29 defeat by Argentina with a rampant attacking display.
England moved their record for 2022 back to five wins and five losses, but the big beasts of New Zealand and South Africa still await in this autumn run.
Smith and Owen Farrell’s midfield partnership even started to bud against the Brave Blossoms, with the playmakers mixing and matching at 10 and 12 to fine effect. The hosts dominated scrum, lineout and tight exchanges too, with far greater potency than in last week’s Pumas loss.
England might struggle to measure the contextual quality of performance at this point given Japan’s limitations – but Jones and company needed a win any which way. And in the event, they conjured far more than that.
England finally found some attacking fluency, with Smith and Farrell frequently trading places to scythe through Japan. Steward strolled in for the first score thanks to England’s potent lineout maul. Farrell stepped in at 10 to tee up Smith for the key pass from 12, and the in-form full-back finished at a canter.
Leicester No 15 Steward launched a stunning counter-attack for England’s second score, racing past halfway before feeding Van Poortvliet, who cut a fine inside line. The sprightly scrum-half shipped on to Joe Cokanasiga, and the Bath wing’s neat pop off the ground sent Smith over in the corner.
England leaked two penalties as Japan forced a foothold, with May sin-binned for killing the ball. Jones’ men were not to be denied however, and still finished the half with their third score despite that numerical disadvantage.
Steward again proved his potency by releasing the hosts for another smart try. The Tigers flier reasserted his dominance under the high ball by regathering his own bomb as the hosts set up camp in the Japan 22.
England forced a quick turnover to stymie the Brave Blossoms’ exit attempts and Sam Simmonds’ lovely in-to-out step in the 13 channel created a walk-in for Porter.
Japan replacement Seung-sin Lee missed a penalty to open the second half, so England ended May’s 10-minute yellow card seven points in credit.
That 24-6 lead quickly became 31-6 as Genge powered home for a smart score. Van Poortvliet cut a neat line off Smith for a dangerous counter, before England swept home through tight carries.
England’s total dominance was confirmed when Farrell stepped in at de facto scrum-half and dinked a defence-turning grubber that Porter gobbled up for his second score.
Farrell’s shrewd and decisive move would always be worthy of acclaim, but Japan should not have been caught so cold. The England captain then slotted the touchline conversion to boot, to leave the hosts 38-6 to the good, before boss Jones started emptying the replacements bench.
Mako Vunipola’s first meaningful involvement was to leak England’s first scrum penalty, as Japan conjured a fine set-piece drive. Warner Deans pilfered ruck ball from England and sent Naoto Saito over for an opportunist score to revive the Japanese, with Lee adding the conversion.
Siosaia Fifita was sin-binned for collapsing a maul as England hit back through their tight-five. The replacement was given his marching orders, while England were awarded a penalty try.
Fifita adopted a nonplussed response as he trudged off, but he was the only one confused with England well on the way to a try before his illegal involvement. Smith then finished off another good score that he had started himself. The fly-half launched a kick-pass to Steward, who collected neatly and chipped in behind the Japan defence.
Replacement Henry Slade flicked on, and Smith swept in to cap a pleasing move. Farrell posted the conversion for a flawless 15-point return from the boot. Not perfect from England, but faster, harder, smarter and smoother will do just fine for now.