Culinary Cuts w/ Severe - Episode 4 - Classic Beef Stroganoff 🔥😋

1.5 lbs ground beef
2 tbsp olive oil , divided
1 large onion (or 2 small onions), sliced
300 g / 10 oz mushrooms , sliced (not too thin)
40 g / 3 tbsp butter
2 tbsp flour
2 cups / 500 ml beef broth
1 tbsp Dijon mustard
150 ml / 2/3 cup sour cream Salt and pepper