Cook the meat and rice. Heat up the beans, and chop the veggies. (Sauté the onions and peppers if desired.)
Make the sauce — note that it has no flour! Melt butter, cream or milk, and cream cheese in a medium saucepan. As it thickens, keep adding more milk or cream — I like it creamy, but not too thin. Add the tomato paste and more taco seasonings, again, about a half-teaspoon each until you see what else it needs – keep whisking it all as it blends together and the flavors “marry”, as the TV chefs say. Taste-test to see what it needs to be dreamy. More sea salt? More garlic powder?
If anything is done before you’re ready to assemble, just set it aside for a few minutes. You can keep the warm stuff on low heat on the stove.
Start assembling. Everyone can throw whatever they like into their burrito bowl. Start with lettuce and/or the rice, and go from there to the meat, veggies, cheese, lime juice, herbs, etc. Dollop the beans, salsa, sour cream, and sauce around the top.