Easy Japanese Curry

I've made this curry a few times before and I like that you can either make it vegetarian or add your meat of choice.  It's healthy, easy, and a good go-to recipe when you don't know what to make for dinner!

Ingredients

1 lb meat (I like using chicken breast or tofu)
4 medium potatoes, diced
3 carrots, halved and sliced
1 cup celery, sliced on a diagonal
1 onion, diced
2 cloves garlic, minced
4 cups chicken broth
5 Tbsp vegetable oil, divided
1/4 cup flour
4 Tbsp curry powder
1 tsp chili powder (optional)
2 tsp salt (or to taste)

Directions

In a large pot, heat 2 Tbsp of vegetable oil. Saute onion and garlic until softened, then add the meat (if using tofu, add with chicken broth).
Add the carrots and potatoes, stir a few times, and then add the chicken broth.
Bring to a boil, and simmer for 15-20 minutes.
While the meat and veggies are cooking, make a roux out of the remaining 3 Tbsp oil and the flour.  Heat oil in a medium skillet until shimmering. Over low-medium heat, add flour and stir, cooking until the flour is blended and takes on a pale golden hue.
Add curry powder and chili powder, using the back of the spatula to blend it into the roux. The mixture will be powdery and dry.
Take 1/2 cup of the hot liquid from the meat pot and slowly add it to the curry-roux mixture, stirring constantly to form a smooth paste.
By spoonfuls, add the curry paste back to the beef mixture, stirring to dissolve.
Add salt to taste.
Simmer the curry for 20-30 minutes, until the sauce has thickened and the beef and vegetables are tender.
Serve curry over brown rice in shallow bowls.