Hot As Hell Texan-Mexican Spinach Dip

YUM YUM

2 tbsp. vegetable oil
1 medium onion, chopped
2 tomatoes, about 3/4 lb..) peeled, seeded, chopped
2 tbsp. canned, chopped jalapeño chilis
1 pkg. (10 oz.)  frozen spinach, thawed, squeezed dry
2 cups grated Monterey Jack cheese (about 7 oz.)
1 pkg. (8 oz.) cream cheese, cut into 1/2" pieces, at room temperature
1 cup half and half
1 tbsp, red wine vinegar
to taste: salt, pepper

Heat oven to 400ºF. Heat oil in heavy medium skillet over medium heat.  Add onion and sauté until softened, stirring occasionally, about 4 minutes.  Add tomatoes and chilis; cook 2 minutes.  Transfer mixture to large bowl and stir in spinach, cheeses, half-and-half, vinegar.  Season with salt and pepper.  Spoon mixture into shallow ovenproof baking dish.  Bake until dip is bubbly and top is browned, about 35 minutes.  Serve with tortilla chips.