Transfer pot to oven; roast sauce, stirring halfway through, until thick and tomatoes are browned on top and around edges of pot, 2 — 2 1/2 hours. (bonappetit.com)
Notice in the picture below how the hot oil forms a circle around the outer edge of the pot. (mexicanfoodjournal.com)
Using a stock pot, the high edges of the pot will keep moisture inside the pot, and during the cooking process moisture will seep out of the vegetables and meat to create its own broth. (thepetstaurant.com)