For the linguine: Bring a large stockpot of water and 1 tablespoon kosher salt to a boil. Add the linguine and cook until al dente, 8 minutes. Drain the linguine, reserving the cooking water. Toss the linguine with the grapeseed oil to prevent sticking.
For the tomato sauce: Add the tomatoes, onions, peppers, garlic and oregano to a large stockpot over low heat. Season with sea salt and pepper. Bring to a simmer, cover, and cook for 1 minute. Add 1 1/2 cups water and the tomato paste and continue simmering for 15 minutes.
For the meatballs: Mix together the ground beef, garlic, red onions, eggs, 1 1/2 teaspoons seasoning salt and 1 teaspoon black pepper in a large bowl. Form the mixture into 1-inch meatballs (14 to 16 meatballs).
Place a large, deep skillet over medium-high heat and coat with the grapeseed oil. Brown the meatballs in the oil, 2 minutes per side. Transfer the meatballs to the sauce and simmer for 5 minutes. Remove the sauce from the heat.
To serve, divide the linguine among 4 serving plates; spoon the sauce over the top. Top each serving with 4 meatballs. Add more sauce if desired.
If you want a thicker sauce, mix in a little of the reserved pasta water, then bring to a simmer and cook for 5 minutes. The starch from the pasta will thicken the sauce.