In a large skillet, brown your lean ground beef over medium heat until it's no longer pink, breaking it apart. If there's any extra fat, drain it off.
Toss in the diced onion and cook until it's nice and soft, about 4 minutes. Stir in the minced garlic and cook for just one more minute.
Stir in the tomato paste and cook for another minute. Sprinkle the flour over the beef and mix well to coat. Gradually pour in the beef broth, stirring continuously to keep it smooth. Add the thyme, paprika, salt, and pepper. Let it gently simmer for 8-10 minutes, stirring now and then, until the sauce thickens nicely. If you're adding veggies, stir in the frozen peas or mixed vegetables now.
For the dumplings, in a separate bowl, whisk together the flour, baking powder, and salt. Add the softened butter and use your fingers or a fork to blend it into the flour until it looks like coarse crumbs. Gently stir in the milk until a soft dough forms. Don't overmix!
Using a spoon, carefully drop generous spoonfuls of the dumpling dough right on top of the simmering beef mixture. Aim for about 6-8 dumplings. Pop a lid on the skillet and reduce the heat to low.
Let those dumplings steam for a good 15 minutes without peeking! They'll puff up beautifully as they cook through from the steam and heat.
Once cooked, take the skillet off the heat and let it rest, uncovered, for 5 minutes. Dish up this comforting meal, ensuring each serving gets some delicious beef and a fluffy dumpling or two. Enjoy!