Heat olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat. Add the ground beef in two batches, breaking it up with a wooden spoon, and cook until deeply browned — about 5–6 minutes per batch. Do not stir too frequently; let the meat develop a crust. Drain off most of the fat, leaving about 2 tablespoons in the pot.

Push the browned beef to the sides of the pot and add the diced onion and green bell pepper to the center. Cook over medium heat, stirring occasionally, until the vegetables are softened and beginning to caramelize — about 5–6 minutes. Add the minced garlic and cook for 1 minute more until fragrant.

Add the chili powder, cumin, smoked paprika, dried oregano, cayenne, salt, and black pepper directly to the pot. Stir everything together and let the spices cook in the fat for 60–90 seconds, stirring constantly, until very fragrant. This step is critical for deep flavor — do not skip it.

Add the tomato paste and stir to coat everything. Cook for 1–2 minutes until the paste darkens slightly and smells rich and slightly caramelized.

Pour in the crushed tomatoes, diced tomatoes with their juices, and beef broth. Stir everything together, scraping up any browned bits from the bottom of the pot — those bits are pure flavor. Add the sugar and bring the pot to a boil.

Reduce the heat to low, partially cover the pot, and simmer for at least 45 minutes, stirring occasionally. For best results, simmer for 60–75 minutes until the chili is thick and deeply flavored. The longer it goes, the better it gets.

Add the drained kidney beans and black beans during the last 20 minutes of cooking. Stir to combine and continue simmering uncovered to let the chili thicken further.

If you want an even thicker chili, whisk the masa harina with ¼ cup cold water until smooth and stir it into the pot during the last 10 minutes of simmering. Cook uncovered, stirring occasionally, until the chili reaches your desired consistency.

Taste the chili and adjust seasoning — add more salt, chili powder, or cayenne as needed. Serve hot in bowls with your choice of toppings: shredded cheddar, sour cream, sliced jalapeños, green onions, and Fritos for crunch.