Brisket, "My Mother's"

Ingredients

• 5 to 6 pound first-cut beef brisket
• 3 tbsp. vegetable oil
• 3 large yellow onions, cut into 1/2" pieces (about 5 cups or 3 pounds)
• 2 or 3 large garlic cloves, or to taste, minced
• 1 tsp. paprika, preferably Hungarian
• 3/4 tsp. salt
• 3/4 tsp. freshly ground pepper