Step #3 In a 3-quart casserole stir together Worchestershire sauce, sugar, oregano, 1/2 c water, beef bouillon granules, 1/2 tsp salt, garlic, & 1/4 tsp pepper.
Step #4 2.
Step #5 Add pot roast to mixture in casserole.
Step #6 Cook, covered, on 100% power (high) about 5 mins or till the liquid is boiling.
Step #7 Cook covered, on 50% power (medium) for 35 mins more.
Step #8 3.
Step #9 Turn pot roast over.
Step #10 Add potatoes, celery, carrots, & onions.
Step #11 Cook meat & vegetables, covered, on medium for 25 to 40 mins or till meat & vegetables are tender, spooning liquid over the meat and vegetables once or twice during cooking.
Step #12 4.
Step #13 Transfer meat & vegetables to a serving platter, reserving the liquid in the casserole.
Step #14 5.
Step #15 For gravy, skim fat from the reserved liquid.
Step #16 stir this together tomato sauce & flour.
Step #17 stir this tomato mixture & mushroom into the liquid in the casserole.
Step #18 Cook uncovered, stirring each min till the mixture starts to thicken, on high for 5 to 10 mins or till thickened & bubbly, then stirring every 30 seconds.
Step #19 Cook, uncovered, on high for 30 seconds more.