Spinach Burgers with Mushroom Sauce

Total time: 30 minutes
     Don't let the greenish tinge to these burgers put you off.  They fry up to a lovely dark, proper burger color, they taste fantastic and you get a healthy dose of vegetables almost without noticing!

 Ingredients:

• 1 large onion
• 2 cloves garlic
• 2 ribs celery
• 4oz (120gr) mushrooms
• 1 egg
• 12oz ground beef (360gr mince)
• 1/2 cup chopped, cooked spinach - or frozen, thawed, & squeezed dry - about 8oz, (240gr)
• 3/4 cup (6oz, 180ml) red wine - 2 tbs for the patties, 2 tbs for the cornstarch and the rest for the sauce
• 1/2 cup bread crumbs
• 1 tsp dried thyme
• 1 cup (8oz, 240ml) beef broth
• 2 tbs tomato paste
• 1 1/2 tbs cornstarch (corn flour, maizena)
• 2 tbs olive oil

 Instructions:

• The vegetables:
• Finely chop onions, celery, mushrooms and garlic.
• In large non-stick skillet over medium heat sauté half of onions, celery, garlic and mushrooms about 5 minutes or until tender.
• Remove from heat and set aside.
• The spinach: 
• If using fresh: roughly chop and add to the skillet for the last minute or until wilted.
• If using frozen: thaw spinach and squeeze out all liquid.
• The burgers: 
• In a large bowl lightly beat the egg.
• Add bread crumbs, 2 tbs of red wine and thyme.
• Mix well, then add the beef, spinach and sautéed onion mixture.
• Mix well - hands work best, and form into 4 patties.
• Heat remaining 1 tbs of oil in the same skillet, add patties and sauté about 5 minutes per side.
• Remove, put on oven-proof plate or platter and put in 250F (125C) oven to keep warm while you finish sauce. 
• The sauce:
• Add remaining onions, celery, garlic and mushrooms to skillet and sauté about 5 minutes or until tender. 
• Add 1/2 cup red wine, beef stock and tomato paste to pan and bring to a boil.
• Dissolve cornstarch in remaining 2 tbs of red wine (or water) and add to sauce, stirring constantly until thickened. 
• Remove patties from oven, pour some of the sauce over and serve with remaining sauce on the side.